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/routes.py

@@ -6,13 +6,10 @@ endpoints that query our own user data from the shared database.
 """
 
 from fastapi import APIRouter, Depends, HTTPException, status
-from pydantic import BaseModel
-from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from cartsnitch_api.auth.dependencies import get_current_user
 from cartsnitch_api.database import get_db
-from cartsnitch_api.models import User
 from cartsnitch_api.schemas import (
     UpdateUserRequest,
     UserResponse,