Skill: Audit Plan

This skill should be used when the user asks to 'audit a plan', 'check plan coverage', 'verify cleanup grep commands', 'audit plan này', 'kiểm tra plan', 'soát plan trước khi implement', or to audit a plan document for gap/test/cleanup coverage before implementation (distinct from /plan-workflow:audit-dead's post-implementation Phase 7 code audit). Sub-commands: gaps, verify, tests. Expects a gap-tracking plan format (### Gap entries, cleanup grep checklist, - [ ] tests); for /plan-workflow:plan-refactor 8-phase plans (## Nhóm/Phase + inline verify: lines) use /plan-workflow:verify-plan instead. Manual-invocation only — direct the user to run /audit-plan:audit-plan rather…