Agent Skills: spec

[Documentation] Use to author, audit, amend, or test-spec a business Feature Spec. The single spec skill — modes draft|init|update|audit|amend create/maintain the tech-free 8-section Feature Spec; draft authors a provisional spec from an idea/requirement (no code yet, Evidence: TBD); tests generates Section 8 TC-{FEATURE}-{NNN} test specifications; sync reconciles §8 TCs ↔ integration test code. Per-mode procedure lives in references/{author,tests,sync}.md.