Write commit message guardrail

[jdelfino]

Write the commit message structure guardrail check.

File

.github/workflows/guardrail-commits.yml

What

• Trigger: PR opened or synchronized
• Check all commits for conventional commit format
• Verify: type prefix (feat/fix/chore/docs/test/refactor), max length, issue reference
• Configurable format from config.yaml
• Non-conforming: neutral (warning, not blocking by default)
• Check for non-stale PR approval override

Reference

• docs/design.md: Commit Message Structure (Layer 4)