Add pyproject.toml for consolidated project configuration and replace Black, isort, and Flake8 with Ruff

- 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.

backend/app/crud/__init__.py

@@ -3,4 +3,4 @@ from .organization import organization
 from .session import session as session_crud
 from .user import user
 
-__all__ = ["user", "session_crud", "organization"]
+__all__ = ["organization", "session_crud", "user"]