ci(.github): add conventional commit validation (pre-commit hook)

[JacobPEvans]

Description

Add commitlint and commit-check pre-commit hooks to validate commit messages locally before they reach GitHub.

Implements

• Local commit message validation
• Block non-compliant commits
• Clear error messages with examples

Tasks

• Add commitlint pre-commit hook to config
• Add commit-check hook
• Test locally with valid/invalid commits
• Document in CONTRIBUTING.md

Depends On

• (GitHub Action for reference)
• (Pre-commit config)

Parent Epic