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/playwright.config.ts

@@ -0,0 +1,29 @@
+import { defineConfig, devices } from "@playwright/test";
+
+const baseURL = process.env.PLAYWRIGHT_BASE_URL ?? "http://localhost:3101";
+const apiURL = process.env.PLAYWRIGHT_API_URL ?? "http://localhost:5080";
+
+export default defineConfig({
+  testDir: "./e2e",
+  fullyParallel: true,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 1 : 0,
+  workers: process.env.CI ? 1 : undefined,
+  reporter: "list",
+  use: {
+    baseURL,
+    trace: "on-first-retry",
+  },
+  projects: [{ name: "chromium", use: { ...devices["Desktop Chrome"] } }],
+  webServer: process.env.CI
+    ? undefined
+    : {
+        command: "npm run dev",
+        url: baseURL,
+        reuseExistingServer: true,
+        timeout: 120_000,
+      },
+  globalSetup: undefined,
+});
+
+export { apiURL };