feat: major dashboard & waiter PWA overhaul

- Manager dashboard: replaced monolithic DashboardTab/OperationsPage with new
  DashboardPage; added OrderDetailModal, ShiftDetailModal, DeleteConfirmModal,
  PaymentMethodModal; updated Sidebar routing and App navigation
- Reports: reworked WorkDaySummary, OrderHistory, ShiftsOverview with detail modals
- Backend routers: extended orders, reports, shifts, products, business_day endpoints;
  updated cloud_sync service
- Waiter PWA: refreshed app icons, improved ConnectionLostModal UX, updated
  TableCard, SSEContext, connectionStore; added useProductCache hook; vite config tweaks

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

waiter_pwa/src/index.css

@@ -667,7 +667,14 @@ html, body {
 .user-menu-item--disabled { color: var(--muted); cursor: not-allowed; }
 .user-menu-item--disabled:hover { background: transparent; }
 .user-menu-item--danger { color: var(--danger); }
-.user-menu-item__icon { font-size: 17px; flex-shrink: 0; }
+.user-menu-item__icon {
+  font-size: 17px;
+  flex-shrink: 0;
+  width: 24px;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+}
 .user-menu-divider {
   height: 1px;
   background: var(--border);