dev-workflow-skills2 Stage 5 Testing 写作 vertical skill。在 progress.md current_stage==testing 且 sub_state ∈ {write, revising} 时写 testing preparation/procedure/report 并执行测试；在 review-passed reentry 中处理初次 fail/partial 的 BUG skeleton → bug-triage、Bug Flow retest pass 的 bug-close、retest fail/partial 的 bug-rework。本 skill 不判 root_cause、不调 bug-start/incident-start、不直接 mutation progress.md。
