Extend Plugin Author

Workflow

1. Read plugins/spec/SPEC.md and the closest example plugin.
2. Identify the target lane, mode, trigger description, required atoms, inputs, and capabilities.
3. Scaffold a plugin folder with SKILL.md, open-design.json, README.md, and evals when useful.
4. Validate JSON and run available repo checks.
5. Prepare publish or PR instructions.

Output Contract

Produce a complete plugin folder and authoring-summary.md.