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/app/globals.css

@@ -3,11 +3,8 @@
 @tailwind utilities;
 
 @layer base {
-  * {
-    @apply border-border;
-  }
   body {
-    @apply bg-background text-foreground;
+    @apply bg-gray-50 text-gray-900;
   }
 }