feat(workflows): add issue plan automation

[activadee]

Summary

• add a reusable issue workflow that calls the codex shared automation
• trigger when the repository owner labels an issue with codex-plan
• pass the issue number to the shared workflow while inheriting repo secrets

Testing

• not run (workflow automation only)

[github-actions]

Codex Review Summary

Recommendation: ✅ Ready to merge – no outstanding findings.

Summary:

• Verify workflow trigger conditions guard against unwanted actors
• Confirm shared workflow references and required inputs are accurate
• Ensure GitHub token permissions and secrets align with least-privilege expectations
  The doc-sync workflow now points at the renamed shared workflow, and the new issue-plan automation is properly gated on owner-applied labels with scoped permissions; no correctness or security concerns surfaced in this review, and other focus areas (stability/maintainability) likewise show no issues.

Findings:

• No findings reported.

Generated at 2025-11-15T23:29:54.821Z.