- Introduced `pyproject.toml` to centralize backend tool configurations (e.g., Ruff, mypy, coverage, pytest).
- Replaced Black, isort, and Flake8 with Ruff for linting, formatting, and import sorting.
- Updated `requirements.txt` to include Ruff and remove replaced tools.
- Added `Makefile` to streamline development workflows with commands for linting, formatting, type-checking, testing, and cleanup.
- Introduced new unit tests for session CRUD operations, including `update_refresh_token`, `cleanup_expired`, and multi-user session handling.
- Added comprehensive tests for `CRUDBase` methods, covering edge cases, error handling, and UUID validation.
- Reduced default test session creation from 5 to 2 for performance optimization.
- Enhanced pagination, filtering, and sorting validations in `get_multi_with_total`.
- Improved error handling with descriptive assertions for database exceptions.
- Introduced tests for eager-loaded relationships in user sessions for comprehensive coverage.
- Deleted `test_crud_base.py`, `test_crud_error_paths.py`, and `test_organization_async.py` due to the removal of corresponding deprecated CRUD implementations.
- Improved codebase maintainability and reduced test suite noise by eliminating obsolete test files.
