- Added a new crate `doc` for API documentation.
- Integrated `utoipa` for OpenAPI support in the presentation layer.
- Updated routes to include social features (follow, unfollow, etc.) and diary export.
- Enhanced API request and response structures with new DTOs for social interactions.
- Updated `Cargo.toml` files to include new dependencies and features.
- Modified Dockerfile to copy the new documentation crate.
- Refactored existing handlers and routes to accommodate new API endpoints.
- Updated tests to cover new functionality and ensure proper API behavior.
