feat(cashier): denomination overdraft validation, exchange detail fix, cash exchange in reports

- Savings/Current/FD/RD withdrawal forms: card-style overdraft warning when
  requested denomination count exceeds cashier stock; submit blocked on overdraft
- Cash History detail view: show both RECEIVED and GIVEN denomination breakdowns
  for Cash Exchange (previously only RECEIVED side was displayed)
- Closing Cash Report: add Cash Exchanges section (denomination-wise received/given/net)
- Excess Transaction Report: include cash exchanges >= threshold with Type badge
  (Exchange/Txn) and ID Proof column for RBI/AML compliance
- cashier-shared.scss: etr-badge and closing-exchange-head styles
- Cash Exchange entry: overdraft warning redesigned to cx-overdraft-card BEM layout

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/cashier/cash-exchange-entry/cash-exchange-entry.component.html

@@ -22,6 +22,49 @@
     </div>
   </header>
 
+  <!-- ── Customer Info Bar ── -->
+  <div class="cx-customer-bar">
+    <div
+      class="cx-customer-toggle"
+      [class.cx-customer-toggle--active]="isAccountHolder"
+      (click)="toggleAccountHolder()"
+    >
+      <mat-icon>{{ isAccountHolder ? 'check_box' : 'check_box_outline_blank' }}</mat-icon>
+      <span>Account Holder</span>
+    </div>
+
+    @if (isAccountHolder) {
+      <label class="cx-field cx-field--inline">
+        <span>Account No.</span>
+        <input
+          type="text"
+          [value]="accountNo"
+          (input)="accountNo = $any($event.target).value"
+          placeholder="e.g. 000101234567"
+        />
+      </label>
+    } @else {
+      <span class="cx-walk-in"><mat-icon>person_outline</mat-icon> Walk-in Customer</span>
+    }
+
+    @if (needsIdProof) {
+      <div class="cx-pan-required">
+        <mat-icon>warning</mat-icon>
+        <span>Amount ≥ ₹50,000 — Customer PAN / Aadhaar required (RBI)</span>
+      </div>
+      <label class="cx-field cx-field--inline cx-field--pan">
+        <span>PAN / Aadhaar *</span>
+        <input
+          type="text"
+          [value]="customerIdProof"
+          (input)="customerIdProof = $any($event.target).value"
+          placeholder="ABCDE1234F"
+          maxlength="20"
+        />
+      </label>
+    }
+  </div>
+
   <div class="cx-cols">
     <!-- RECEIVED -->
     <section class="cx-col cx-col--received">
@@ -147,14 +190,42 @@
   @if (receivedTotal > 0 && !matches) {
     <div class="cx-warn"><mat-icon>warning</mat-icon> Received and Given totals must match (net ₹0).</div>
   }
+  @if (hasGivenOverdraft) {
+    <div class="cx-overdraft-card">
+      <div class="cx-overdraft-card__title">
+        <mat-icon class="cx-overdraft-card__ico">block</mat-icon>
+        <span>Insufficient stock — cannot give to customer</span>
+      </div>
+      <div class="cx-overdraft-card__rows">
+        @for (item of givenOverdraftItems; track item.label) {
+          <div class="cx-overdraft-card__row">
+            <span class="cx-overdraft-card__chip">{{ item.label }}</span>
+            <span class="cx-overdraft-card__stat"
+              ><span class="cx-overdraft-card__lbl">Need</span><strong>{{ item.requested }}</strong></span
+            >
+            <span class="cx-overdraft-card__dot">·</span>
+            <span class="cx-overdraft-card__stat"
+              ><span class="cx-overdraft-card__lbl">Available</span><strong>{{ item.available }}</strong></span
+            >
+            <span class="cx-overdraft-card__short">Short: {{ item.requested - item.available }}</span>
+          </div>
+        }
+      </div>
+    </div>
+  }
+  @if (needsIdProof && !customerIdProof.trim()) {
+    <div class="cx-warn cx-warn--pan">
+      <mat-icon>badge</mat-icon> Enter customer PAN / Aadhaar to proceed (amount ≥ ₹50,000).
+    </div>
+  }
 
   <div class="cx-actions">
     <label class="cx-field cx-field--note">
       <span>Note</span>
       <input type="text" [value]="note" (input)="note = $any($event.target).value" placeholder="Optional" />
     </label>
-    <button type="button" class="cx-btn cx-btn--primary" [disabled]="!matches || saving" (click)="submit()">
-      <mat-icon>swap_horiz</mat-icon> Confirm Exchange
+    <button type="button" class="cx-btn cx-btn--primary" [disabled]="!valid || saving" (click)="submit()">
+      <mat-icon>swap_horiz</mat-icon> {{ saving ? 'Saving…' : 'Confirm Exchange' }}
     </button>
   </div>
 </div>