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/app/[locale]/(dashboard)/layout.tsx

@@ -0,0 +1,59 @@
+"use client";
+
+import { useEffect } from "react";
+import { useLocale } from "next-intl";
+import { useRouter } from "@/i18n/routing";
+import { Sidebar } from "@/components/layout/sidebar";
+import { Topbar } from "@/components/layout/topbar";
+import { CafeThemeProvider } from "@/components/theme/cafe-theme-provider";
+import { useAuthStore } from "@/lib/stores/auth.store";
+import { useOfflineSync } from "@/lib/offline/use-offline-sync";
+
+export default function DashboardLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  const locale = useLocale();
+  const router = useRouter();
+  const user = useAuthStore((s) => s.user);
+  useOfflineSync(); // register online/offline listeners + load queue count
+
+  useEffect(() => {
+    if (!user?.accessToken) {
+      router.replace("/login");
+    }
+  }, [user, router]);
+
+  const isRtl = locale !== "en";
+
+  const mainColumn = (
+    <div className="flex min-h-0 min-w-0 flex-1 flex-col">
+      <Topbar />
+      <main className="min-h-0 flex-1 overflow-auto p-6 bg-background">
+        {children}
+      </main>
+    </div>
+  );
+
+  return (
+    <CafeThemeProvider>
+      <div
+        className="flex h-screen min-h-0 overflow-hidden bg-background"
+        dir={isRtl ? "rtl" : "ltr"}
+      >
+        {isRtl ? (
+          <>
+            <Sidebar side="right" />
+            {mainColumn}
+          </>
+        ) : (
+          <>
+            <Sidebar side="left" />
+            {mainColumn}
+          </>
+        )}
+      </div>
+    </CafeThemeProvider>
+  );
+}