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/cashier-shared.scss

@@ -373,3 +373,58 @@
     font-variant-numeric: tabular-nums;
   }
 }
+
+/* ── Cash Exchange section header ───────────────────────────────────── */
+.closing-exchange-head {
+  display: flex;
+  align-items: flex-start;
+  gap: 10px;
+  padding: 12px 16px 10px;
+  border-bottom: 1px solid #e2e8f0;
+  margin-bottom: 2px;
+
+  mat-icon {
+    color: #0f4f3c;
+    font-size: 22px;
+    height: 22px;
+    width: 22px;
+    margin-top: 2px;
+    flex-shrink: 0;
+  }
+}
+
+.closing-exchange-title {
+  font-size: 14px;
+  font-weight: 700;
+  color: #1a1a1a;
+}
+
+.closing-exchange-sub {
+  font-size: 12px;
+  color: #64748b;
+  margin-top: 2px;
+}
+
+// Excess Transaction Report — type badges
+.etr-badge {
+  display: inline-flex;
+  align-items: center;
+  height: 22px;
+  padding: 0 8px;
+  border-radius: 5px;
+  font-size: 11px;
+  font-weight: 700;
+  white-space: nowrap;
+
+  &--savings {
+    background: #f0fdf4;
+    color: #15803d;
+    border: 1px solid #bbf7d0;
+  }
+
+  &--exchange {
+    background: #eff6ff;
+    color: #1d4ed8;
+    border: 1px solid #bfdbfe;
+  }
+}