feat(clerk): add clerk-facing Cheque Book screen and shell nav wiring

Adds a customer-account-scoped Cheque Book view under Clerk > Account
Facilities (list + leaf detail, with stop-payment/report-lost/mark-used/
return actions), reachable via a new hover dropdown on the Account
Facilities nav item. Also refreshes the Account Facilities page layout,
and carries over a few chequebook service/detail-dialog fixes from the
back-office module (used-leaf display, leaf-lookup dialog polish).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/chequebook/cheque-book-detail/cheque-book-detail.component.html

@@ -73,6 +73,9 @@
       <button mat-stroked-button color="primary" (click)="startAction('markused')">
         {{ 'labels.buttons.Mark as Used' | translate }}
       </button>
+      <button mat-stroked-button color="warn" (click)="startAction('return')">
+        {{ 'labels.buttons.Flag Returned' | translate }}
+      </button>
     </div>
   }
 
@@ -130,7 +133,9 @@
                   ? 'warn'
                   : l.status === 'LOST'
                     ? 'bad'
-                    : 'neutral'
+                    : l.status === 'RETURNED'
+                      ? 'returned'
+                      : 'neutral'
           "
           (click)="selectLeaf(l)"
         >