Add Maintainer Mode

[jacobbabula]

Adds Maintainer Mode to Development & Workflow.

• Source: https://github.com/jacobbabula/maintainer-mode
• Release: https://github.com/jacobbabula/maintainer-mode/releases/tag/v0.1.0
• HOL Plugin Scanner: 97/100 (A)
• Hosted scanner: https://github.com/jacobbabula/maintainer-mode/actions/runs/31986674142
• Findings: 0 critical, high, medium, or low

Maintainer Mode gives Codex an evidence gate for open-source work: stale or conflicting issues become ASK, and test claims become PROVEN only when receipts match a single commit and worktree.

This PR adds only the single alphabetical README entry requested by CONTRIBUTING.md.

[github-actions]

@jacobbabula — this pull request needs updates before it can be merged.

Contribution requirements failed

Required scanner CI is missing or could not be validated.

• jacobbabula/maintainer-mode: https://github.com/jacobbabula/maintainer-mode does not expose readable GitHub Actions workflows: source repository or workflow directory was not found

How to fix it

1. Add a workflow under .github/workflows/ in the linked source repository.
2. Trigger it on both push and pull_request, and invoke hashgraph-online/ai-plugin-scanner-action.
3. Configure plugin_dir: ".", mode: scan, min_score: 80, and fail_on_severity: high.
4. Keep .codex-plugin/plugin.json, README.md, SECURITY.md, LICENSE, and a dependency lockfile in the source repository.

See the repository's contribution requirements and scanner guide.

After pushing the changes, this check and comment will update automatically: https://github.com/hashgraph-online/awesome-codex-plugins/actions/runs/33146379886