feat(rbi-reserve,savings): Form 1/Form 9 returns UI, branch-wise interest posting reports and summary

- Reports > Interest Posting Reports: per branch and product, generate/regenerate
  at any time, approve; branch column, HO-on-behalf marker, posted txn per account
- Reports > Interest Posting Summary (branch-wise) for the head office, with Excel export
- Day Close warns and disables Close Day while the branch's interest report is unapproved
- Savings product accounting: Interest On Savings (expense), Savings Interest Payable
  and Paid (liability rows, required)
- RBI Form 1 statutory and Form 9 return screens, reserve config updates
- Interest posting report GETs exempted from the response cache

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/app/cashier/branch-day/branch-day.component.ts

@@ -189,6 +189,23 @@ export class BranchDayComponent implements OnInit {
     return this.totalOf(this.closeCounts);
   }
 
+  /**
+   * Savings products whose interest posting report is due today and not yet approved. The close is
+   * refused by the backend while any is pending; this only says so before the user tries.
+   */
+  interestPending: string[] = [];
+
+  private checkInterestReports(): void {
+    if (!this.openDay?.businessDate) {
+      this.interestPending = [];
+      return;
+    }
+    this.service
+      .interestDayCloseCheck(this.openDay.businessDate, this.openDay.officeId)
+      .pipe(catchError(() => of(null)))
+      .subscribe((res) => (this.interestPending = res?.pendingProducts ?? []));
+  }
+
   load(): void {
     this.loading = true;
     this.errorMsg = '';
@@ -210,6 +227,7 @@ export class BranchDayComponent implements OnInit {
         this.canOperate = !!res?.canOperate;
         this.openDate = this.today;
         this.checkFirstOpenCashMigration();
+        this.checkInterestReports();
       });
 
     this.service