docs: add pre-commit hooks section to CONTRIBUTING.md (#117)

CONTRIBUTING.md

@@ -16,6 +16,38 @@
 - Test changes before submitting
 - See [VERSIONING.md](VERSIONING.md) for backport compatibility rules
 
+## Pre-commit Hooks
+
+This repository uses [pre-commit](https://pre-commit.com/) for linting and commit message enforcement.
+
+### Setup
+
+```bash
+pip install pre-commit
+pre-commit install
+```
+
+### Hooks
+
+- **shellcheck** — Lints bash scripts
+- **ruff** — Lints and formats Python
+- **commitizen** — Enforces [Conventional Commits](https://www.conventionalcommits.org/) format
+
+### Commit Message Format
+
+Use Conventional Commits format:
+
+```
+type(scope): message
+
+# Examples
+fix(session): handle missing session gracefully
+feat(pm): add queue daemon for task delegation
+docs: update contributing guide
+```
+
+Types: `fix`, `feat`, `docs`, `refactor`, `chore`, `test`
+
 ## Branches
 
 ### Primary Branches