feat: Denomination Master admin UI (modern fintech design)

Standalone Angular page to manage currency notes & coins: hero + stat
tiles, notes/coins card grids, slide-in drawer for add/edit. Supports
CRUD, enable/disable, and client-side duplicate (denomination+kind)
validation with snackbar feedback. Added route and Admin menu link.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/core/shell/shell.component.html

@@ -404,6 +404,10 @@
             <fa-icon icon="key" class="menu-item-icon" style="color: #7c3aed"></fa-icon>
             OTP Audit Logs
           </button>
+          <button mat-menu-item routerLink="/system/denomination-master" tabindex="0">
+            <fa-icon icon="coins" class="menu-item-icon" style="color: #7c3aed"></fa-icon>
+            Denomination Master
+          </button>
         </div>
 
         <!-- Audit & Compliance -->