[thatsrue]

What changed

Adds lefthook.yml with a pre-push job that runs make lint typecheck test-fast, and a line in docs/README.md and AGENTS.md on enabling it with lefthook install. The job clears git's repo variables first, so it runs from a linked worktree.

Why

CI runs ruff, mypy and pytest -m "not slow" on every pull request. A push should not need CI to find a failure the local checks would. The package build job is not in the hook.

Closes #83

How you checked it

• make lint typecheck test-fast from a fresh worktree of origin/main: exit 0, 7 s (296 passed)
• lefthook run pre-push --force (lefthook 2.2.2): exit 0, 4 s. Run again with GIT_DIR and GIT_INDEX_FILE exported: exit 0, 4 s
• A bug fix comes with a test that fails without it (not a bug fix)
• Docs match how it works now
• No secrets or private information

The worktree needs its own .venv, as make uses it.