precommit.md

Run the pre-commit checklist for this project:

1. Remind me to update CHANGELOG.md [Unreleased] section (Added / Changed / Fixed / Removed) — I must do this manually.
2. Run uv run flake8 . — must pass.
3. Run uv run black --check . — must pass (run uv run black . to auto-fix).
4. Run uv run pytest --cov=./ --cov-report=term — all tests must pass, coverage must be ≥80%.

Run steps 2–4, report the results clearly, then propose a branch name and commit message for my approval using the format type(scope): description (#issue) (max 80 chars; types: feat fix chore docs test refactor ci perf). Do not create the branch or commit until I explicitly confirm.