feat: add prek pre-commit hooks

[edvardm]

Note

prek is just a suggestion -- many other pre-commit hook managers would likely do the job

Summary

Adds opt-in pre-commit hooks via prek — a Rust rewrite of pre-commit, drop-in compatible with the same .pre-commit-config.yaml format. Notable adopters: Home Assistant, CPython, Apache Airflow, FastAPI, Ruff, vLLM (Airflow reported 10x speedup over pre-commit).

Hooks

Hook	Stage	Scope
end-of-file-fixer	commit	.py, .yaml, .toml, .md
trailing-whitespace	commit	.py, .yaml, .toml, .md
check-merge-conflict	commit	all files
ruff-check	commit	Python (auto-fix)
ruff-format	commit	Python
committed	commit-msg	enforces Conventional Commits

Setup

uv run prek install
uv run prek install --hook-type commit-msg

Hooks are opt-in — not enforced on contributors, but probably should be enforced via CI.