brooks-lint, New Skill Scaffold

Skill name comes from the user request (kebab-case, e.g. brooks-security). If empty, ask for the name and a one-line purpose first.

Follow the repo's "Adding a New Skill" checklist exactly:

1. Create skills/{name}/SKILL.md with frontmatter, name, a description that ends with a Do NOT trigger for: clause (validate-enforced for shipped skills; omitting it causes false triggering), metadata: with opencode/slash: "true", and a Process section of 3, 6 bullets that cite the guide's step ranges inline (e.g. Scan risks (Steps 1, 6 of the guide)). Mirror the structure of an existing skill such as skills/brooks-review/SKILL.md (Setup → Process → Mode line).
2. Create skills/{name}/{name}-guide.md with sequentially numbered steps, no gaps, no duplicates. Sub-steps like Step 2a are allowed. The guide owns the detailed steps; the SKILL.md Process is just an orientation skeleton.
3. Wire the framework. The new SKILL.md Setup section must Read the relevant _shared/ files (common.md for Iron Law + Report Template, plus decay-risks.md / test-decay-risks.md as applicable), _shared/ is NOT auto-loaded.
4. Add eval coverage to evals/evals.json: append with the next sequential id at least one happy-path scenario (with the relevant risk code in expected_output) and at least one false-positive scenario flagged no_risk_codes: true. Each scenario needs id, name, prompt, expected_output, mode, files.
5. Validate. npm run validate (structure + step continuity + Process-section presence) and npm run evals (eval schema). Fix until both pass.
6. Local-test. Link the new skill folder from skills/ into .agents/skills/ alongside the _shared symlink, then invoke it with $<skill-name> in a Codex session and verify the Iron Law output.