chore: add pre-commit ruff hook with auto-fix

- scripts/hooks/pre-commit: runs ruff --fix for root and web/ (matching CI)
  and re-stages any auto-fixed files so they land in the commit
- Makefile: add install-hooks target (run once after clone)
- pyproject.toml: exclude web/ from root ruff (web has its own config)
- Fix remaining import sort warnings caught by the new hook

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/tests/conftest.py

@@ -7,7 +7,6 @@ from unittest.mock import AsyncMock, patch
 
 import aiosqlite
 import pytest
-
 from beanflows import core
 from beanflows.app import create_app