Adds .githooks/pre-push that runs cargo fmt --check, cargo clippy
-- -D warnings, and cargo test before every push. Enable with:
git config core.hooksPath .githooks
Skip with git push --no-verify for rapid iteration.
Documented in README.md and CONTRIBUTING.md.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
