- Disable OpenAPI docs/redoc/openapi.json when APP_ENV=production
- Strip uvicorn Server header with --no-server-header in Dockerfile and docker-compose.yml
- Add OriginValidatorMiddleware to reject state-changing requests from disallowed origins
- Add global exception handler to prevent stack trace leakage on unhandled errors
- Add tests for all new security features (OpenAPI, origin validation, exception handler, server header)
