feat(investment): settle purchases from Holdings; broken-period interest to settlement date

- Purchases are saved as Pending Settlement. Holdings show the status and
  a Settle button (from the settlement date), and the GL transaction id
  once settled.
- The transaction log shows "Not posted (pending settlement)" until a
  deal is settled, and dates the purchase on its settlement date.
- Broken-period interest is counted up to the settlement date.
- Accounting Preview title and the Holdings Settlement Date column
  reflect settlement-date posting.

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

src/app/investment/bond-investment/bond-investment.component.ts

@@ -239,17 +239,19 @@ export class BondInvestmentComponent implements OnInit {
     });
   }
 
+  /** A purchase reaches the GL only when it is settled, dated the settlement date. */
   private purchaseTxn(d: InvestmentPurchaseDto): InvestmentTxn {
+    const posted = !!d.glTransactionId;
     return {
       certNo: d.certNo,
       instrumentType: d.bondType,
       txnType: 'PURCHASE',
       voucherNo: `INV/PUR/${d.dealNo}`,
-      txnDate: d.dealDate,
+      txnDate: d.settlementDate,
       amount: d.settlementAmount,
       particulars: `Purchase Deal ${d.dealNo} - ${d.scriptDesc} - ${d.partyName} [${d.category}]`,
-      glCode: d.investmentGlCode,
-      glName: d.investmentGlName
+      glCode: posted ? d.investmentGlCode : '',
+      glName: posted ? `${d.investmentGlName} (txn ${d.glTransactionId})` : 'Not posted (pending settlement)'
     };
   }
 
@@ -573,20 +575,19 @@ export class BondInvestmentComponent implements OnInit {
     return approxYtm(f.intRate, f.purchaseRate || 100, yearsBetween(f.issueDate, this.purchaseMaturityDate));
   }
 
-  /** Accrued Interest at purchase — interest earned by the seller since the last coupon date. */
-  /** Interest owed to the seller from the last coupon date up to the deal date, on a 30/360 basis —
-   *  interest is counted to the event date, not the date the money moves (Jitendra Sir). */
+  /** Broken-period interest owed to the seller from the last coupon date up to the settlement date, 30/360. */
   get purchaseAccruedInterest(): number {
     const f = this.purchaseForm;
     if (!f.intRate || !f.lastIntDt || !f.dealDate) {
       return 0;
     }
-    return Math.round((this.purchaseBaseAmount * (f.intRate / 100) * days360(f.lastIntDt, f.dealDate)) / 360);
+    return Math.round((this.purchaseBaseAmount * (f.intRate / 100) * this.purchaseAccruedDays) / 360);
   }
 
   get purchaseAccruedDays(): number {
     const f = this.purchaseForm;
-    return f.lastIntDt && f.dealDate ? days360(f.lastIntDt, f.dealDate) : 0;
+    // Up to the settlement date, when the bond leaves the seller (RBI para 83; Jitendra Sir).
+    return f.lastIntDt && this.purchaseSettlementDate ? days360(f.lastIntDt, this.purchaseSettlementDate) : 0;
   }
 
   /** Premium (+) or discount (−) paid over face value. */
@@ -842,7 +843,9 @@ export class BondInvestmentComponent implements OnInit {
     };
     this.investmentService.createPurchase(body).subscribe({
       next: (res) => {
-        this.toast(`Deal ${res.resourceIdentifier} saved. GL posting will follow once accounting is approved.`);
+        this.toast(
+          `Deal ${res.resourceIdentifier} saved — pending settlement. Settle it from Holdings on or after the settlement date.`
+        );
         this.activeTab = 'holdings';
         this.loadPurchases();
       },
@@ -941,6 +944,24 @@ export class BondInvestmentComponent implements OnInit {
     this.toast(`Deal for Cert No ${h.certNo} retrieved.`);
   }
 
+  /** Posts a pending deal to GL dated its settlement date; under maker-checker it waits in the Checker Inbox. */
+  settleDeal(h: InvestmentHolding): void {
+    if (!h.id) {
+      return;
+    }
+    this.investmentService.settlePurchase(h.id).subscribe({
+      next: (res) => {
+        this.toast(
+          res.rollbackTransaction
+            ? `Settlement of deal ${h.dealNo} sent for approval (Checker Inbox).`
+            : `Deal ${h.dealNo} settled and posted to GL (transaction ${res.transactionId}).`
+        );
+        this.loadPurchases();
+      },
+      error: (err) => this.toast(apiErrorMessage(err))
+    });
+  }
+
   dropPurchase(): void {
     const h = this.holdings.find((x) => x.certNo === this.purchaseForm.certNo);
     if (!h?.id) {