- Introduced caching headers (`Cache-Control`, `ETag`, `Last-Modified`) for file responses to improve client-side caching.
- Added HTTP admin routes for health check and authentication validation.
- Made `cache_max_age` configurable via server configuration with a default of 3600 seconds.
- Enhanced file handler with metadata-based `Last-Modified` computation.
- Updated integration tests to cover new functionality and ensure correctness.