Adapt for self-hosted deployment on Coolify

- Replace @vercel/postgres with standard pg library
- Add Dockerfile for Next.js standalone build
- Add tsconfig.json, postcss.config.js
- Fix globals.css undefined tailwind utilities
- Force dynamic rendering for DB-dependent pages
- Add .dockerignore

frontend/package.json

@@ -14,7 +14,7 @@
     "react": "^18",
     "react-dom": "^18",
     "pg": "^8.11.3",
-    "@vercel/postgres": "^0.5.1"
+    "@types/pg": "^8.10.9"
   },
   "devDependencies": {
     "@types/node": "^20",