feat: comprehensive seed, Lucide icons, grouped dashboard nav, API fixes

- Rewrite prisma/seed.ts to populate all 27 models with realistic
  Vietnamese real estate data (8 users with login, 10 properties,
  10 listings, orders, payments, reviews, notifications, etc.)
- Replace all emoji icons with Lucide React SVG icons across frontend
  for consistent rendering, sizing, and accessibility
- Redesign dashboard nav: grouped sidebar with section headers,
  primary/secondary split on desktop, icon-only secondary items
- Replace language switcher flag emoji with Globe icon
- Replace SVG theme toggle with Lucide Moon/Sun icons
- Fix API startup: graceful fallback for Sentry profiling, Google OAuth,
  and Zalo OAuth when credentials are not configured
- Relax rate limiting in development mode (10k req/min)
- Fix listings API to include media[] array in search response
- Add optional chaining for property.media across frontend components
- Update OAuth strategy tests to match graceful fallback behavior

Co-Authored-By: Claude Opus 4 (1M context) <noreply@anthropic.com>

apps/web/lib/listings-api.ts

@@ -67,6 +67,7 @@ export interface ListingDetail {
     latitude: number | null;
     longitude: number | null;
     media: PropertyMedia[];
+    thumbnail?: string | null;
   };
   seller: {
     id: string;