feat: configure Coolify deployment for production

- Fix docker-compose.yml for production: use postgres:15-alpine, remove
  container names, remove postgres external port, set FRONTEND_URL to
  server IP, use empty VITE_API_URL for nginx proxy
- Add production server CORS origins to backend
- Add deploy job to GitHub Actions CI/CD pipeline

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/main.py

@@ -282,6 +282,9 @@ allowed_origins = [
     "http://localhost:8080",
     "http://127.0.0.1:80",
     "http://127.0.0.1:8080",
+    # Production server (Coolify)
+    "http://194.187.253.230:3010",
+    "http://194.187.253.230",
 ]
 
 # Add production domain from environment variable