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/menu-item-image.ts

@@ -0,0 +1,52 @@
+import { Coffee, CupSoda, UtensilsCrossed, type LucideIcon } from "lucide-react";
+import { resolveMediaUrl } from "@/lib/api/client";
+
+export type MenuItemVisualKind = "food" | "drink";
+
+const DRINK_CATEGORY_IDS = new Set(["cat_demo_drinks", "cat_demo_cold"]);
+
+/** Latin keywords; Persian/Arabic category names come from API `categoryName`. */
+const DRINK_HINTS = [
+  "drink",
+  "cold",
+  "hot",
+  "coffee",
+  "tea",
+  "juice",
+  "smoothie",
+  "beverage",
+  "bar",
+  "espresso",
+  "latte",
+];
+
+export function inferMenuItemKind(
+  categoryId: string,
+  categoryName?: string
+): MenuItemVisualKind {
+  if (DRINK_CATEGORY_IDS.has(categoryId)) return "drink";
+
+  const haystack = `${categoryId} ${categoryName ?? ""}`.toLowerCase();
+  if (DRINK_HINTS.some((h) => haystack.includes(h))) return "drink";
+
+  return "food";
+}
+
+export function getMenuItemImageSrc(imageUrl?: string | null): string | undefined {
+  return resolveMediaUrl(imageUrl);
+}
+
+export function menuItemPlaceholderIcon(kind: MenuItemVisualKind): LucideIcon {
+  return kind === "drink" ? CupSoda : UtensilsCrossed;
+}
+
+/** Larger hero-style icon for sidebar preview */
+export function menuItemPlaceholderHeroIcon(kind: MenuItemVisualKind): LucideIcon {
+  return kind === "drink" ? Coffee : UtensilsCrossed;
+}
+
+export function buildCategoryNameMap(
+  categories: { id: string; name: string }[]
+): Map<string, string> {
+  return new Map(categories.map((c) => [c.id, c.name]));
+}