Greptile Summary

This PR hardens CI/CD security by pinning all third-party GitHub Actions to immutable commit SHAs instead of mutable version tags, making the workflow supply chain deterministic and auditable.

• All actions in main.yml, release-please.yml, and the new lint-pr-title.yml are now pinned with version comments for traceability
• The new PR title validation workflow uses pull_request_target appropriately with read-only permissions and no code checkout
• Added .vscode/settings.json for consistent YAML formatting in workflow files

Confidence Score: 5/5

• This PR is safe to merge with minimal risk - implements security best practices for GitHub Actions
• All changes are configuration-only, improve security posture, follow GitHub's recommended practices for action pinning, and include version comments for maintainability. No functional code changes or security risks introduced.
• No files require special attention

Important Files Changed

_{Last reviewed commit: 548e22b}