feat(cashier): full double-entry journal view + Excel export for Cash/Clearing/Transfer Summary

Transaction Details now renders each voucher as a paired Dr/Cr journal entry with a
derived contra account and a Balanced status chip, so both sides of a transaction are
visible at a glance for reconciliation. Adds a shared cashier-export.ts (mirrors the
Investment module's exporter) and an Export to Excel button producing a Summary +
Transaction Details workbook, plus a Branch Breakup sheet for Head Office consolidated view.

src/app/cashier/cash-clearing-transfer-summary/cash-clearing-transfer-summary.component.html

@@ -31,6 +31,9 @@
       <button type="button" class="pg-btn" [class.pg-btn--active]="showDetails" (click)="toggleDetails()">
         {{ showDetails ? 'Summary View' : 'Transaction Details' }}
       </button>
+      <button type="button" class="pg-btn pg-btn--ghost" [disabled]="generating" (click)="exportExcel()">
+        {{ generating ? 'Exporting…' : 'Export to Excel' }}
+      </button>
     </div>
   </header>
 
@@ -209,43 +212,61 @@
                 ? 'Clearing'
                 : 'Digital'
         }}
-        — Transaction Details
+        — Transaction Details (Full Double Entry)
         @if (glFilter !== null) {
           · {{ glFilter }}
         }
       </div>
-      <table class="pg-table">
+      <table class="pg-table cctr-journal">
         <thead>
           <tr>
             <th>Date</th>
             <th>Voucher / Ref No</th>
-            <th>Account No</th>
-            <th>Account Name / Reference</th>
-            <th>Particulars</th>
+            <th>Dr / Cr</th>
+            <th>GL / Account</th>
             <th class="num col-out">Debit</th>
             <th class="num col-in">Credit</th>
+            <th>Status</th>
           </tr>
         </thead>
         <tbody>
           @for (t of filteredTxns; track t.voucherNo) {
-            <tr>
+            <tr class="cctr-journal-row cctr-journal-row--first">
               <td>{{ asOnDate }}</td>
               <td>
                 <span class="pg-chip">{{ display(t.voucherNo) }}</span>
               </td>
-              <td>{{ display(t.accountNo) }}</td>
-              <td>{{ t.accountName }}</td>
-              <td>{{ t.particulars }}</td>
-              <td class="num col-out">
+              <td><span class="cctr-drcr cctr-drcr--dr">Dr</span></td>
+              <td>
                 @if (t.debit > 0) {
-                  ₹{{ t.debit | number: '1.2-2' }}
+                  <span class="pg-chip">{{ t.glCode }}</span> {{ glName(t.glCode) }} — {{ display(t.accountNo) }} ({{
+                    t.accountName
+                  }})
+                } @else {
+                  <span class="cctr-contra">{{ contraLabel(t) }}</span>
                 }
               </td>
-              <td class="num col-in">
+              <td class="num col-out">₹{{ legAmount(t) | number: '1.2-2' }}</td>
+              <td class="num"></td>
+              <td rowspan="2">
+                <span class="cctr-balanced-chip">✓ Balanced</span>
+              </td>
+            </tr>
+            <tr class="cctr-journal-row cctr-journal-row--second">
+              <td></td>
+              <td></td>
+              <td><span class="cctr-drcr cctr-drcr--cr">Cr</span></td>
+              <td>
                 @if (t.credit > 0) {
-                  ₹{{ t.credit | number: '1.2-2' }}
+                  <span class="pg-chip">{{ t.glCode }}</span> {{ glName(t.glCode) }} — {{ display(t.accountNo) }} ({{
+                    t.accountName
+                  }})
+                } @else {
+                  <span class="cctr-contra">{{ contraLabel(t) }}</span>
                 }
               </td>
+              <td class="num"></td>
+              <td class="num col-in">₹{{ legAmount(t) | number: '1.2-2' }}</td>
             </tr>
           } @empty {
             <tr>
@@ -255,9 +276,14 @@
         </tbody>
         <tfoot>
           <tr class="cctr-total-row">
-            <td colspan="5">Total</td>
-            <td class="num">₹{{ txnTotal(filteredTxns, 'debit') | number: '1.2-2' }}</td>
-            <td class="num">₹{{ txnTotal(filteredTxns, 'credit') | number: '1.2-2' }}</td>
+            <td colspan="4">Total ({{ filteredTxns.length }} vouchers)</td>
+            <td class="num">
+              ₹{{ txnTotal(filteredTxns, 'debit') + txnTotal(filteredTxns, 'credit') | number: '1.2-2' }}
+            </td>
+            <td class="num">
+              ₹{{ txnTotal(filteredTxns, 'debit') + txnTotal(filteredTxns, 'credit') | number: '1.2-2' }}
+            </td>
+            <td></td>
           </tr>
         </tfoot>
       </table>