feat: migrate frontend to Astro + expand AI moderation + backend admin/runtime config

Frontend:
- migrate from Vite to Astro (astro.config.mjs, pages/, layouts/)
- add admin panel, settings page, command palette, error boundary
- refactor App.tsx, MascotChatbot, Sidebar, Header, DashboardLayout
- update API client, WebSocket, auth, dashboard features

Backend:
- add admin module and config routes
- refactor middlewares, Redis connection, WebSocket server/bridge
- add runtime config loader

Discord Gateway:
- refactor AI moderation: circuit breaker, concurrency limiter, fallback processor
- add media analysis client, Seaxng search, user profile learner
- add new drizzle migration

Shared:
- extend database schema, add new config fields

services/backend/package.json

@@ -17,9 +17,11 @@
     "@bete/shared": "workspace:*",
     "@discordjs/voice": "^0.19.2",
     "axios": "^1.16.1",
+    "cors": "^2.8.6",
     "dotenv": "^17.4.2",
     "drizzle-orm": "^0.45.2",
     "express": "^5.2.1",
+    "express-rate-limit": "^8.5.2",
     "helmet": "^8.1.0",
     "ioredis": "^5.11.0",
     "pg": "^8.21.0",
@@ -30,12 +32,14 @@
   },
   "devDependencies": {
     "@biomejs/biome": "latest",
+    "@types/cors": "^2.8.19",
     "@types/express": "^5.0.6",
+    "@types/express-rate-limit": "^6.0.2",
     "@types/node": "^25.9.0",
+    "@types/pg": "^8.20.0",
     "@types/ws": "^8.18.1",
     "tsx": "^4.22.2",
     "typescript": "^5.9.3",
-    "@types/pg": "^8.20.0",
     "vitest": "latest"
   }
 }