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/components/ui/card.tsx

@@ -0,0 +1,33 @@
+import * as React from "react";
+import { cn } from "@/lib/utils";
+
+const Card = React.forwardRef<HTMLDivElement, React.HTMLAttributes<HTMLDivElement>>(
+  ({ className, ...props }, ref) => (
+    <div
+      ref={ref}
+      className={cn(
+        "rounded-xl border bg-card text-card-foreground shadow-sm",
+        className
+      )}
+      {...props}
+    />
+  )
+);
+Card.displayName = "Card";
+
+const CardHeader = ({ className, ...props }: React.HTMLAttributes<HTMLDivElement>) => (
+  <div className={cn("flex flex-col space-y-1.5 p-6", className)} {...props} />
+);
+
+const CardTitle = ({ className, ...props }: React.HTMLAttributes<HTMLHeadingElement>) => (
+  <h3
+    className={cn("text-2xl font-semibold leading-none tracking-tight", className)}
+    {...props}
+  />
+);
+
+const CardContent = ({ className, ...props }: React.HTMLAttributes<HTMLDivElement>) => (
+  <div className={cn("p-6 pt-0", className)} {...props} />
+);
+
+export { Card, CardHeader, CardTitle, CardContent };