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/organization/rbi-reserve-config/rbi-reserve-config.component.html

@@ -129,11 +129,30 @@
 
     <!-- ═══ GL accounts ═══ -->
     <div class="rrc-card">
-      <h3 class="rrc-card__title">GL accounts behind each figure</h3>
+      <div class="rrc-gl-head">
+        <h3 class="rrc-card__title">GL accounts behind each figure</h3>
+        <!--
+          The two returns share a base but maintain their requirement in different assets, so an
+          administrator setting one up is looking at a different set of heads than one setting up
+          the other. Showing all of them at once buries the few that matter for the task in hand.
+        -->
+        <mat-form-field appearance="outline" subscriptSizing="dynamic" class="rrc-gl-head__filter">
+          <mat-label>Configuring</mat-label>
+          <mat-select [(ngModel)]="formFilter" (selectionChange)="onFormFilterChange()">
+            @for (f of formFilters; track f.value) {
+              <mat-option [value]="f.value">{{ f.label }}</mat-option>
+            }
+          </mat-select>
+        </mat-form-field>
+      </div>
       <p class="rrc-card__hint">
         Every role takes as many accounts as it needs — a bank holds current accounts at several other banks, and each
         one counts toward what it maintains. Only postable accounts are listed: a header account's balance is the sum of
         its children, so mapping both would count those children twice.
+        @if (formFilter !== 'ALL') {
+          Heads that build or net the DTL base are shown for either return, since both charge their rate on that same
+          base.
+        }
       </p>
 
       @if (unmappedCount) {