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/investment.service.ts

@@ -12,6 +12,7 @@ import { Observable, forkJoin } from 'rxjs';
 import { map, tap } from 'rxjs/operators';
 import {
   DailyScriptRate,
+  HoldingStatus,
   InstrumentType,
   InvestmentHolding,
   PARTY_MASTER,
@@ -119,6 +120,8 @@ export interface InvestmentPurchaseDto {
   crGlName: string;
   otherDetails?: string;
   status: string;
+  glTransactionId?: string;
+  settledOnDate?: string;
 }
 
 export interface InvestmentGlAccount {
@@ -200,6 +203,14 @@ export class InvestmentService {
     return this.http.delete(`/investment/daily-rates/${rateId}`);
   }
 
+  /** Settles a deal: posts it to GL dated its settlement date. Under maker-checker the response only says it awaits approval. */
+  settlePurchase(purchaseId: number): Observable<{ transactionId?: string; rollbackTransaction?: boolean }> {
+    return this.http.post<{ transactionId?: string; rollbackTransaction?: boolean }>(
+      `/investment/purchases/${purchaseId}/settle`,
+      {}
+    );
+  }
+
   createPurchase(body: object): Observable<{ resourceId: number; resourceIdentifier: string }> {
     return this.http.post<{ resourceId: number; resourceIdentifier: string }>('/investment/purchases', body);
   }
@@ -316,7 +327,9 @@ export function toHolding(p: InvestmentPurchaseDto): InvestmentHolding {
     glName: p.investmentGlName,
     crToAc: p.crGlCode,
     brokerCode: '',
-    status: 'ACTIVE',
+    status: p.status as HoldingStatus,
+    settlementDate: p.settlementDate,
+    glTransactionId: p.glTransactionId,
     category: p.category,
     bookValue: p.bookValue,
     settlementAmount: p.settlementAmount