Document native agent maintenance workflows

[chubes4]

Summary

• direct the developer-docs agent to document the two native maintenance workflows
• cover their writable boundaries, verification contract, and no-op behavior

Testing

1. Run pnpm build.
2. Run pnpm verify.
3. Dispatch the Build With WordPress Developer Docs Agent workflow and review its generated documentation PR.

AI assistance

• AI assistance: Yes
• Tool(s): OpenAI GPT-5.6 Sol via OpenCode
• Used for: Drafted the workflow prompt update and verified the generated plugin outputs.