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/alembic/versions/7396957cbe80_initial_empty_migration.py

@@ -1,19 +1,18 @@
 """Initial empty migration
 
 Revision ID: 7396957cbe80
-Revises: 
+Revises:
 Create Date: 2025-02-27 12:47:46.445313
 
 """
-from typing import Sequence, Union
 
-from alembic import op
+from collections.abc import Sequence
 
 # revision identifiers, used by Alembic.
-revision: str = '7396957cbe80'
-down_revision: Union[str, None] = None
-branch_labels: Union[str, Sequence[str], None] = None
-depends_on: Union[str, Sequence[str], None] = None
+revision: str = "7396957cbe80"
+down_revision: str | None = None
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
 
 
 def upgrade() -> None: