- Added List import and field_validator to config.py
- Added database connection pooling settings (max_overflow, pool_recycle, pool_pre_ping, echo)
- Added rate limiting settings (rate_limit_requests, rate_limit_window_seconds)
- Added CORS allow_origins field with default empty list
- Added validate_secrets() method to check required secrets in production
- Added validate_secret_length() validator for secret_key and jwt_secret (minimum