Fix ruff lint errors across codebase

- Auto-fix F401 (unused imports) and I001 (unsorted imports) with ruff --fix
- Manually fix E501 (line too long) in alembic migrations and src/ models
- Run ruff format to ensure consistent formatting

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/cartsnitch_api/auth/dependencies.py

@@ -5,7 +5,8 @@ Sessions are verified by querying the shared sessions table directly.
 """
 
 from datetime import UTC, datetime
-from fastapi import Cookie, Depends, Header, HTTPException, Request, status
+
+from fastapi import Depends, Header, HTTPException, Request, status
 from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
 from sqlalchemy import text
 from sqlalchemy.ext.asyncio import AsyncSession