feat(dashboard): Next.js 16 merchant panel with offline POS and PWA

Complete merchant dashboard upgrade:

Next.js 16 compatibility:
- Fix params/searchParams typed as Promise<{}> throughout App Router
- Replace middleware.ts with proxy.ts (Next.js 16 convention)
- Remove unused @ts-expect-error directives caught by stricter TS
- Cast dynamic next-intl t() keys to fix TranslateArgs type errors

Offline POS:
- IndexedDB queue (meezi_pos_offline) for orders created while offline
- Zustand sync store tracking queueCount, isSyncing, isOnline
- useOfflineSync hook: auto-syncs on reconnect/visibility-change
- SyncStatusIndicator chip in topbar (amber=offline, blue=syncing)
- submitOrderToApi falls back to local order on network failure
- Local orders skip payment flow; sync on reconnect

PWA (installable):
- @ducanh2912/next-pwa with Workbox runtime caching rules
- Web App Manifest (manifest.ts) — RTL/Farsi, theme #0F6E56
- PWA icons: 192px, 512px, maskable 512px
- next.config.ts replaces next.config.mjs

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

web/dashboard/src/lib/pos-order-label.ts

@@ -0,0 +1,17 @@
+import type { Order } from "@/lib/api/types";
+
+/** Label for open orders at pay time: table + guest name. */
+export function formatPosOrderLabel(
+  order: Pick<Order, "tableNumber" | "guestName" | "customerName">,
+  tableWord: string
+): string {
+  const parts: string[] = [];
+  if (order.tableNumber) {
+    parts.push(`${tableWord} ${order.tableNumber}`);
+  }
+  const name = order.guestName?.trim() || order.customerName?.trim();
+  if (name) {
+    parts.push(name);
+  }
+  return parts.length > 0 ? parts.join(" · ") : "—";
+}