CI: Add PR title verifier workflow

[rubambiza]

Summary

• Adds a caller workflow that invokes the org-level reusable PR title verifier from kagenti/.github
• Enforces PR title prefix conventions (Feat, Fix, Docs, etc.) on all pull requests
• No changes to existing workflows or repo configuration

[rubambiza]

Update: The reusable workflow in kagenti/.github is now live (PR #66 merged), so this caller workflow will fire correctly as soon as this PR is merged.

However, the pinned SHA in this workflow will need a final bump once kagenti/.github#67 merges. That PR adds FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true to suppress a Node.js 20 deprecation warning from the action-pr-title action (GitHub is removing Node 20 runner support on September 16, 2026). The action itself is safe for Node 24 (only uses @actions/core and @actions/github).

Once #67 merges, I'll push an updated SHA pin to this branch.

[ChristianZaccaria]

/lgtm !!

[cwiklik]

Clean caller workflow — pinned to SHA, permissions: {}, proper trigger types. No issues.

Areas reviewed: CI/GitHub Actions
Commits: 6, all signed-off
CI: all passing