- Introduced rate-limiting to `/auth/*` routes with configurable limits using `SlowAPI`.
- Added `/health` endpoint for service monitoring and load balancer health checks.
- Updated `requirements.txt` to include `SlowAPI` for rate limiting.
- Implemented tests for rate-limiting and health check functionality.
- Enhanced configuration and security with updated environment variables, pinned dependencies, and validation adjustments.
- Provided example usage and extended coverage in testing.