feat(investment): wire Bank/Party, Script Master and Purchase Entry to the backend

- Bank / Party Master and Script Master follow the bank's existing CBS
  screens (address, bank type, GL A/c, RBI code, limit, LEI, counterparty
  bank details; SLR type, auto script code, ISIN, interest rate, issue /
  maturity date, auto period, company details) and save to
  /investment/parties and /investment/scripts. GL dropdowns list enabled
  ASSET detail accounts from the chart of accounts.
- Purchase Entry simplified to the mandatory fields; script details,
  settlement date, last interest date, units, book value, premium/discount,
  accrued interest (30/360 up to the deal date), settlement amount and YTM
  are filled automatically; optional fields sit under "More Details";
  an Accounting Preview shows the GL entry. Save / Retrieve / Drop use
  /investment/purchases and the Holdings register lists saved purchases.
- New InvestmentService for the investment API calls.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/investment/investment-data.ts

@@ -123,6 +123,16 @@ export interface InvestmentHolding {
    *  never re-counts days up to this date, so re-running a Calculation & Post for an overlapping
    *  or repeated period always yields 0 instead of double-posting the same interest. */
   interestPostedTillDate?: string;
+  /** RBI investment category chosen at purchase — HTM / AFS / HFT. */
+  category?: string;
+  /** SGL / CSGL account the security is held in (custody, not an accounting GL). */
+  sglAccountNo?: string;
+  /** Backend id / deal number / party code once the purchase is saved (absent on sample rows). */
+  id?: number;
+  dealNo?: string;
+  partyCode?: string;
+  bookValue?: number;
+  settlementAmount?: number;
 }
 
 export interface InvestmentTxn {
@@ -248,6 +258,51 @@ export function accruedInterestBetween(h: InvestmentHolding, fromStr: string, to
   return Math.round(h.faceValue * (h.interestRate / 100) * (days / 365.25));
 }
 
+/** Days between two DD-MM-YYYY dates on a 30/360 basis (every month 30 days), as the bank's existing
+ *  CBS counts them — e.g. 10-08 → 30-09 = 50 days, 10-08 → 07-10 = 57 days. */
+export function days360(fromStr: string, toStr: string): number {
+  const a = parseDDMMYYYY(fromStr);
+  const b = parseDDMMYYYY(toStr);
+  if (isNaN(a.getTime()) || isNaN(b.getTime()) || b <= a) {
+    return 0;
+  }
+  const d1 = Math.min(a.getDate(), 30);
+  const d2 = Math.min(b.getDate(), 30);
+  return (b.getFullYear() - a.getFullYear()) * 360 + (b.getMonth() - a.getMonth()) * 30 + (d2 - d1);
+}
+
+/** Most recent half-yearly coupon date on or before `onStr`, derived from the maturity date (coupons
+ *  fall on the maturity day/month and six months either side of it). */
+export function lastHalfYearlyCouponDate(maturityStr: string, onStr: string): string {
+  const mat = parseDDMMYYYY(maturityStr);
+  const on = parseDDMMYYYY(onStr);
+  if (isNaN(mat.getTime()) || isNaN(on.getTime())) {
+    return '';
+  }
+  const day = mat.getDate();
+  const couponOn = (year: number, month: number): Date => {
+    const lastDay = new Date(year, month + 1, 0).getDate();
+    return new Date(year, month, Math.min(day, lastDay));
+  };
+  const months = [
+    mat.getMonth() % 6,
+    (mat.getMonth() % 6) + 6
+  ];
+  let best: Date | undefined;
+  for (const year of [
+    on.getFullYear() - 1,
+    on.getFullYear()
+  ]) {
+    for (const m of months) {
+      const c = couponOn(year, m);
+      if (c <= on && (!best || c > best)) {
+        best = c;
+      }
+    }
+  }
+  return best ? formatDDMMYYYY(best) : '';
+}
+
 export function formatDDMMYYYY(d: Date): string {
   return `${String(d.getDate()).padStart(2, '0')}-${String(d.getMonth() + 1).padStart(2, '0')}-${d.getFullYear()}`;
 }
@@ -1404,99 +1459,319 @@ export const CASH_BANK_GL_MASTER: InvestmentGlOption[] = [
   { glCode: '110030', glName: 'HDFC BANK CURRENT ACCOUNT' }
 ];
 
+/** Investment GLs a script / party can be mapped to. PROPOSED codes awaiting approval — the
+ *  backend will take these from the chart of accounts, never hard-coded. */
+export const INVESTMENT_GL_OPTIONS: InvestmentGlOption[] = [
+  { glCode: '100701', glName: 'INVESTMENT IN CENTRAL GOVT SECURITIES' },
+  { glCode: '100702', glName: 'INVESTMENT IN STATE GOVT SECURITIES' },
+  { glCode: '100703', glName: 'INVESTMENT IN BONDS / DEBENTURES' },
+  { glCode: '100704', glName: 'FIXED DEPOSITS WITH OTHER BANKS' },
+  { glCode: '100705', glName: 'INVESTMENT IN MUTUAL FUNDS' },
+  { glCode: '100706', glName: 'INVESTMENT IN SHARES' }
+];
+
+/** Fallback investment GL when a script has none mapped. */
+export const INVESTMENT_GL_BY_TYPE: Record<InstrumentType, string> = {
+  GOVT_SECURITY: '100701',
+  NON_SLR: '100703',
+  BOND: '100703',
+  FD: '100704',
+  MUTUAL_FUND: '100705',
+  SHARE: '100706'
+};
+
+/** Interest receivable (the senior's "Provision A/c") — debited for interest bought from the seller. */
+export const INTEREST_RECEIVABLE_GL: InvestmentGlOption = {
+  glCode: '100603',
+  glName: 'INTEREST RECEIVABLE ON INVESTMENTS (PROVISION)'
+};
+
+/** Bank accounts a purchase can be paid from — these GLs already exist in the chart of accounts. */
+export const SETTLEMENT_BANK_GL_OPTIONS: InvestmentGlOption[] = [
+  { glCode: '100201', glName: 'IDBI BANK' },
+  { glCode: '100202', glName: 'YES BANK' }
+];
+
+/** Every GL the Investment screens can show by name. */
+export const INVESTMENT_GL_LOOKUP: InvestmentGlOption[] = [
+  ...INVESTMENT_GL_OPTIONS,
+  INTEREST_RECEIVABLE_GL,
+  ...SETTLEMENT_BANK_GL_OPTIONS
+];
+
+/** SLR classification on the Script Master, as in the bank's existing CBS ("GOI" = Central Govt). */
+export type SlrType = 'GOI' | 'STATE_GOVT' | 'TREASURY' | 'NON_SLR';
+
+export const SLR_TYPE_OPTIONS: Array<{ value: SlrType; label: string }> = [
+  { value: 'GOI', label: 'GOI' },
+  { value: 'STATE_GOVT', label: 'STATE GOVT' },
+  { value: 'TREASURY', label: 'TREASURY' },
+  { value: 'NON_SLR', label: 'NON SLR' }
+];
+
 export interface ScriptMaster {
+  /** Backend id once the script is saved (absent on the sample rows). */
+  id?: number;
   scriptCode: string;
   scriptName: string;
   instrumentType: InstrumentType;
   isin: string;
   faceValuePerUnit: number;
+  // Fields below follow the bank's existing CBS Script Master; a purchase picks them up instead
+  // of the dealer re-typing them on every deal.
+  slrType?: SlrType;
+  /** Investment GL this script is booked to. */
+  glAccountId?: number;
+  glCode?: string;
+  glName?: string;
+  active?: boolean;
+  /** Interest (coupon) rate % per annum. */
+  couponRate?: number;
+  issueDate?: string;
+  maturityDate?: string;
+  // Issuer details — used for Bond / Mutual Fund scripts.
+  companyName?: string;
+  address1?: string;
+  address2?: string;
+  address3?: string;
+  city?: string;
+  pincode?: string;
+  phone?: string;
+  fax?: string;
+  corpCode?: string;
+}
+
+/** Period between two DD-MM-YYYY dates as years / months / days, as shown on the Script Master. */
+export function periodBetween(fromStr?: string, toStr?: string): { years: number; months: number; days: number } {
+  const none = { years: 0, months: 0, days: 0 };
+  if (!fromStr || !toStr) {
+    return none;
+  }
+  const from = parseDDMMYYYY(fromStr);
+  const to = parseDDMMYYYY(toStr);
+  if (isNaN(from.getTime()) || isNaN(to.getTime()) || to < from) {
+    return none;
+  }
+  let years = to.getFullYear() - from.getFullYear();
+  let months = to.getMonth() - from.getMonth();
+  let days = to.getDate() - from.getDate();
+  if (days < 0) {
+    months -= 1;
+    days += new Date(to.getFullYear(), to.getMonth(), 0).getDate();
+  }
+  if (months < 0) {
+    years -= 1;
+    months += 12;
+  }
+  return { years, months, days };
 }
 
 export const SCRIPT_MASTER: ScriptMaster[] = [
-  { scriptCode: 'FD-CUM', scriptName: 'Cumulative Fixed Deposit', instrumentType: 'FD', isin: '', faceValuePerUnit: 1 },
+  {
+    scriptCode: 'FD-CUM',
+    scriptName: 'Cumulative Fixed Deposit',
+    instrumentType: 'FD',
+    isin: '',
+    faceValuePerUnit: 1,
+    slrType: 'NON_SLR',
+    glCode: '100704'
+  },
   {
     scriptCode: 'FD-MIP',
     scriptName: 'Monthly Interest Payout FD',
     instrumentType: 'FD',
     isin: '',
-    faceValuePerUnit: 1
+    faceValuePerUnit: 1,
+    slrType: 'NON_SLR',
+    glCode: '100704'
   },
   {
     scriptCode: 'IN0020230012',
     scriptName: '7.26% GOI 2033',
     instrumentType: 'GOVT_SECURITY',
     isin: 'IN0020230012',
-    faceValuePerUnit: 100
+    faceValuePerUnit: 100,
+    slrType: 'GOI',
+    glCode: '100701',
+    couponRate: 7.26,
+    issueDate: '15-01-2023',
+    maturityDate: '15-01-2033'
   },
   {
     scriptCode: 'IN0020220089',
     scriptName: '7.10% GOI 2029',
     instrumentType: 'GOVT_SECURITY',
     isin: 'IN0020220089',
-    faceValuePerUnit: 100
+    faceValuePerUnit: 100,
+    slrType: 'GOI',
+    glCode: '100701',
+    couponRate: 7.1,
+    issueDate: '10-03-2022',
+    maturityDate: '10-03-2029'
+  },
+  {
+    scriptCode: 'IN0020210056',
+    scriptName: '6.79% GOI 2027',
+    instrumentType: 'GOVT_SECURITY',
+    isin: 'IN0020210056',
+    faceValuePerUnit: 100,
+    slrType: 'GOI',
+    glCode: '100701',
+    couponRate: 6.79,
+    issueDate: '05-06-2021',
+    maturityDate: '05-06-2027'
+  },
+  {
+    scriptCode: 'IN0020240034',
+    scriptName: '7.18% GOI 2037',
+    instrumentType: 'GOVT_SECURITY',
+    isin: 'IN0020240034',
+    faceValuePerUnit: 100,
+    slrType: 'GOI',
+    glCode: '100701',
+    couponRate: 7.18,
+    issueDate: '22-04-2024',
+    maturityDate: '22-04-2037'
+  },
+  {
+    scriptCode: 'MH-SDL-2031',
+    scriptName: '8.05% Maharashtra SDL 2031',
+    instrumentType: 'GOVT_SECURITY',
+    isin: '',
+    faceValuePerUnit: 100,
+    slrType: 'STATE_GOVT',
+    glCode: '100702',
+    couponRate: 8.05,
+    issueDate: '15-02-2021',
+    maturityDate: '15-02-2031'
+  },
+  {
+    scriptCode: 'GJ-SDL-2026',
+    scriptName: '7.85% Gujarat SDL 2026',
+    instrumentType: 'GOVT_SECURITY',
+    isin: '',
+    faceValuePerUnit: 100,
+    slrType: 'STATE_GOVT',
+    glCode: '100702',
+    couponRate: 7.85,
+    issueDate: '18-09-2016',
+    maturityDate: '18-09-2026'
   },
   {
     scriptCode: 'TBILL-364D',
     scriptName: '364 Days Treasury Bill',
     instrumentType: 'GOVT_SECURITY',
     isin: '',
-    faceValuePerUnit: 100
+    faceValuePerUnit: 100,
+    slrType: 'TREASURY',
+    glCode: '100701',
+    couponRate: 0,
+    issueDate: '02-07-2026',
+    maturityDate: '02-07-2027'
+  },
+  {
+    scriptCode: 'TBILL-91D',
+    scriptName: '91 Days Treasury Bill',
+    instrumentType: 'GOVT_SECURITY',
+    isin: '',
+    faceValuePerUnit: 100,
+    slrType: 'TREASURY',
+    glCode: '100701',
+    couponRate: 0,
+    issueDate: '15-05-2026',
+    maturityDate: '13-08-2026'
   },
   {
     scriptCode: 'REC-7.5-2031',
     scriptName: 'REC Ltd Bond 7.50% 2031',
     instrumentType: 'NON_SLR',
     isin: 'INE020B08JN0',
-    faceValuePerUnit: 100
+    faceValuePerUnit: 100,
+    slrType: 'NON_SLR',
+    glCode: '100703',
+    couponRate: 7.5,
+    issueDate: '11-08-2021',
+    maturityDate: '11-08-2031',
+    companyName: 'REC Limited',
+    city: 'New Delhi'
   },
   {
     scriptCode: 'NABARD-7.35-2030',
     scriptName: 'NABARD Bond 7.35% 2030',
     instrumentType: 'NON_SLR',
     isin: 'INE261F09EU1',
-    faceValuePerUnit: 100
+    faceValuePerUnit: 100,
+    slrType: 'NON_SLR',
+    glCode: '100703',
+    couponRate: 7.35,
+    issueDate: '20-09-2020',
+    maturityDate: '20-09-2030',
+    companyName: 'NABARD',
+    city: 'Mumbai'
   },
   {
     scriptCode: 'LTF-8.1-2028',
     scriptName: 'L&T Finance NCD 8.10% 2028',
     instrumentType: 'BOND',
     isin: 'INE027E07BR5',
-    faceValuePerUnit: 100
+    faceValuePerUnit: 100,
+    slrType: 'NON_SLR',
+    glCode: '100703',
+    couponRate: 8.1,
+    companyName: 'L&T Finance Ltd',
+    city: 'Mumbai'
   },
   {
     scriptCode: 'BAF-7.95-2027',
     scriptName: 'Bajaj Finance NCD 7.95% 2027',
     instrumentType: 'BOND',
     isin: 'INE296A07SP0',
-    faceValuePerUnit: 100
+    faceValuePerUnit: 100,
+    slrType: 'NON_SLR',
+    glCode: '100703',
+    couponRate: 7.95,
+    companyName: 'Bajaj Finance Ltd',
+    city: 'Pune'
   },
   {
     scriptCode: 'SBI-OVN',
     scriptName: 'SBI Overnight Fund',
     instrumentType: 'MUTUAL_FUND',
     isin: 'INF200KA1Q40',
-    faceValuePerUnit: 1000
+    faceValuePerUnit: 1000,
+    slrType: 'NON_SLR',
+    glCode: '100705',
+    companyName: 'SBI Mutual Fund',
+    city: 'Mumbai'
   },
   {
     scriptCode: 'HDFC-LIQ',
     scriptName: 'HDFC Liquid Fund',
     instrumentType: 'MUTUAL_FUND',
     isin: 'INF179KA1WR9',
-    faceValuePerUnit: 1000
+    faceValuePerUnit: 1000,
+    slrType: 'NON_SLR',
+    glCode: '100705',
+    companyName: 'HDFC Mutual Fund',
+    city: 'Mumbai'
   },
   {
     scriptCode: 'SBIN',
     scriptName: 'State Bank of India',
     instrumentType: 'SHARE',
     isin: 'INE062A01020',
-    faceValuePerUnit: 1
+    faceValuePerUnit: 1,
+    slrType: 'NON_SLR',
+    glCode: '100706'
   },
   {
     scriptCode: 'HDFCBANK',
     scriptName: 'HDFC Bank Ltd',
     instrumentType: 'SHARE',
     isin: 'INE040A01034',
-    faceValuePerUnit: 1
+    faceValuePerUnit: 1,
+    slrType: 'NON_SLR',
+    glCode: '100706'
   }
 ];
 
@@ -1561,23 +1836,150 @@ export const BROKER_MASTER: BrokerMaster[] = [
 ];
 
 export interface PartyMaster {
+  /** Backend id once the party is saved (absent on the sample rows). */
+  id?: number;
   partyCode: string;
   partyName: string;
   partyType: 'BANK' | 'CORPORATE' | 'GOVT' | 'AMC' | 'EXCHANGE' | 'COOP_SOCIETY';
-  panNo: string;
+  panNo?: string;
+  // Fields below follow the bank's existing CBS Bank / Party Master.
+  bondType?: InstrumentType;
+  address1?: string;
+  address2?: string;
+  address3?: string;
+  city?: string;
+  pincode?: string;
+  phone?: string;
+  fax?: string;
+  bankType?: string;
+  /** GL this party is mapped to. */
+  glAccountId?: number;
+  glCode?: string;
+  glName?: string;
+  rbiCode?: string;
+  /** Exposure limit for this party (₹). */
+  limit?: number | null;
+  leiNo?: string;
+  // Counterparty's bank details
+  cpBankName?: string;
+  cpBranchName?: string;
+  cpAccountNo?: string;
+  cpIfsc?: string;
+  /** Absent means ACTIVE. An INACTIVE party is not offered for new deals. */
+  status?: 'ACTIVE' | 'INACTIVE';
 }
 
+/** Sample Bank Type options until the bank confirms its list. */
+export const BANK_TYPE_OPTIONS = [
+  'SCHEDULED COMMERCIAL BANK',
+  'STATE CO-OPERATIVE BANK',
+  'DISTRICT CENTRAL CO-OPERATIVE BANK',
+  'URBAN CO-OPERATIVE BANK',
+  'RBI / GOVERNMENT',
+  'OTHER'
+];
+
 export const PARTY_MASTER: PartyMaster[] = [
-  { partyCode: 'PTY-001', partyName: 'Jila Sahakari Kendriya Bank', partyType: 'BANK', panNo: 'AABCJ1234K' },
-  { partyCode: 'PTY-002', partyName: 'State Cooperative Bank Ltd', partyType: 'BANK', panNo: 'AABCS5678L' },
-  { partyCode: 'PTY-003', partyName: 'RBI - SGL', partyType: 'GOVT', panNo: 'AAACR4849R' },
-  { partyCode: 'PTY-004', partyName: 'REC Limited', partyType: 'CORPORATE', panNo: 'AAACR0641G' },
-  { partyCode: 'PTY-005', partyName: 'NABARD', partyType: 'CORPORATE', panNo: 'AAACN0272B' },
-  { partyCode: 'PTY-006', partyName: 'L&T Finance Ltd', partyType: 'CORPORATE', panNo: 'AAACL0140P' },
-  { partyCode: 'PTY-007', partyName: 'SBI Mutual Fund', partyType: 'AMC', panNo: 'AAATS4325L' },
-  { partyCode: 'PTY-008', partyName: 'HDFC Mutual Fund', partyType: 'AMC', panNo: 'AAATH1234M' },
-  { partyCode: 'PTY-009', partyName: 'NSE/BSE', partyType: 'EXCHANGE', panNo: 'AAACN0028G' },
-  { partyCode: 'PTY-010', partyName: 'District Cooperative Bank', partyType: 'COOP_SOCIETY', panNo: 'AABCD9988K' }
+  {
+    partyCode: 'PTY-001',
+    partyName: 'Jila Sahakari Kendriya Bank',
+    partyType: 'BANK',
+    bondType: 'FD',
+    glCode: '100704',
+    city: 'Vidisha',
+    bankType: 'DISTRICT CENTRAL CO-OPERATIVE BANK',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-002',
+    partyName: 'State Cooperative Bank Ltd',
+    partyType: 'BANK',
+    bondType: 'FD',
+    glCode: '100704',
+    city: 'Bhopal',
+    bankType: 'STATE CO-OPERATIVE BANK',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-003',
+    partyName: 'RBI - SGL',
+    partyType: 'GOVT',
+    bondType: 'GOVT_SECURITY',
+    glCode: '100701',
+    city: 'Mumbai',
+    bankType: 'RBI / GOVERNMENT',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-004',
+    partyName: 'REC Limited',
+    partyType: 'CORPORATE',
+    bondType: 'NON_SLR',
+    glCode: '100703',
+    city: 'New Delhi',
+    bankType: 'OTHER',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-005',
+    partyName: 'NABARD',
+    partyType: 'CORPORATE',
+    bondType: 'NON_SLR',
+    glCode: '100703',
+    city: 'Mumbai',
+    bankType: 'OTHER',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-006',
+    partyName: 'L&T Finance Ltd',
+    partyType: 'CORPORATE',
+    bondType: 'BOND',
+    glCode: '100703',
+    city: 'Mumbai',
+    bankType: 'OTHER',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-007',
+    partyName: 'SBI Mutual Fund',
+    partyType: 'AMC',
+    bondType: 'MUTUAL_FUND',
+    glCode: '100705',
+    city: 'Mumbai',
+    bankType: 'OTHER',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-008',
+    partyName: 'HDFC Mutual Fund',
+    partyType: 'AMC',
+    bondType: 'MUTUAL_FUND',
+    glCode: '100705',
+    city: 'Mumbai',
+    bankType: 'OTHER',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-009',
+    partyName: 'NSE/BSE',
+    partyType: 'EXCHANGE',
+    bondType: 'SHARE',
+    glCode: '100706',
+    city: 'Mumbai',
+    bankType: 'OTHER',
+    status: 'ACTIVE'
+  },
+  {
+    partyCode: 'PTY-010',
+    partyName: 'District Cooperative Bank',
+    partyType: 'COOP_SOCIETY',
+    bondType: 'SHARE',
+    glCode: '100706',
+    city: 'Vidisha',
+    bankType: 'DISTRICT CENTRAL CO-OPERATIVE BANK',
+    status: 'ACTIVE'
+  }
 ];
 
 export interface SubTypeMaster {