feat: add production deployment config

- Add docker-compose.prod.yml and Caddyfile for Caddy reverse proxy
- Add production stages to frontend Dockerfile (nginx for static files)
- Fix monorepo package exports for production builds (dist/src paths)
- Add CORS_ORIGIN env var for cross-origin config
- Add Better Auth baseURL, cookie domain, and trusted origins from env
- Use VITE_API_URL for API calls in auth-client and play route
- Add credentials: include for cross-origin fetch requests
- Remove unused users table from schema

.env.example

@@ -1,5 +1,12 @@
-DATABASE_URL=postgres://postgres:mypassword@db-host:5432/postgres
+DATABASE_URL=postgres://postgres:mypassword@db-host:5432/databasename
 
 POSTGRES_USER=postgres
 POSTGRES_PASSWORD=postgres
 POSTGRES_DB=databasename
+
+BETTER_AUTH_SECRET=
+BETTER_AUTH_URL=
+GOOGLE_CLIENT_ID=
+GOOGLE_CLIENT_SECRET=
+GITHUB_CLIENT_ID=
+GITHUB_CLIENT_SECRET=