feat(skill-check): 新增 skill-check 技能——例行稽核整個技能組是否符合準則

What(改了什麼)：
- 新增 skills/skill-check/SKILL.md：六步流程——依 Gitea 正本 marketplace 同步全部 domain repo → 每個 domain 各派一個 sub agent 對照 guidelines 審核檢查清單稽核 → 不符項目逐項走 jsc-ask:ask 決策樹確認（套用建議修正／略過／自訂修正，每個選項標明影響範圍）→ 每個受影響 repo 各派一個 sub agent 套用修正（含 README「Skills 目錄」同步與三份 manifest 版本遞增）→ 複檢至全數通過 → 逐 repo 以 jsc-git:pr 開 PR。
- README.md「Skills 目錄」新增 skill-check 條目，並標明與 skillset-update 的分工：無變更需求走 skill-check，有變更需求走 skillset-update。

Why(為什麼改)：
- 既有 skillset-update 以「一份變更需求」為前提；準則本身演進後，技能組缺少「無變更需求時」的例行體檢入口，不符項目只能等到下次改動才被發現。
- 稽核與修正拆成獨立技能，可排入定期維護，讓整個技能組持續符合 guidelines.md。

How(怎麼改)：
- 依 guidelines.md 準則撰寫：英文 description 含觸發與不觸發時機（套用變更需求改用 skillset-update、單一技能改用 skill-update）、Gitea 操作一律走 jsc-gitea/tools/gitea.sh、提問一律走 jsc-ask:ask、需隔離的步驟標明 MUST run as a sub agent、每步標明完成條件。
- 複檢失敗時明定回到決策樹確認步驟，直到檢查清單全數通過才開 PR。

Who(影響哪個功能／使用者)：
- 負責 jsc 技能組例行維護的維護者；一般技能新增、更新、刪除的使用者不受影響（仍走 skill-new／skill-update／skill-delete）。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -38,6 +38,10 @@ Marketplace 統一為 `jsc`（https://gitea.jsc.idv.tw/plugins/jsc.git），安
 
 批次更新——把一份變更需求套用到整個技能組的多個技能／domain，逐 repo 開 PR；單一技能改用 skill-update。
 
+### `skill-check`
+
+例行稽核——沒有變更需求時，把整個技能組逐一對照準則的審核檢查清單：sub agent 逐 domain 稽核 → 不符項目逐項決策樹確認 → sub agent 套用修正並複檢 → 逐 repo 開 PR。有變更需求改用 skillset-update。
+
 ### `ste100-sync`
 
 同步上游 speak-human-tw 的語言規則：比對 `references/ste100.md` 釘住的上游版本，有新版就萃取適用的變更、更新 lint 樣式、全庫重掃，最後開 PR。適合列為本 repo 的維護方式。

skills/skill-check/SKILL.md

@@ -0,0 +1,17 @@
+---
+name: skill-check
+description: Routine compliance audit of the whole jsc skill set with no change request in hand. Sync every domain repo from the Gitea canonical marketplace, audit every skill against the guidelines.md audit checklist via sub agents, confirm each failed item with the user via decision tree, apply the confirmed fixes and re-check until all items pass, then open a PR per affected repo via jsc-git pr. Use for periodic or on-demand compliance checks of the skill set; not for applying a change request (use skillset-update) or editing one skill (use skill-update).
+---
+
+# skill-check — audit the skill set against the guidelines
+
+Single source of guidelines: [`../../references/guidelines.md`](../../references/guidelines.md).
+
+## Flow
+
+1. Query the Gitea canonical marketplace for the authoritative domain list: run `jsc-gitea/tools/gitea.sh api GET /repos/plugins/jsc/raw/.claude-plugin/marketplace.json`. Clone any domain repo missing from the working directory (`gitea.sh clone-url plugins/{domain}`) and pull the rest. Completion condition: every domain repo exists locally and is current.
+2. Audit every skill of every domain against the guidelines.md audit checklist — this step MUST run as a sub agent, one sub agent per domain repo. Each sub agent reports its findings: skill, failed checklist item, evidence (file:line), proposed fix. Completion condition: every domain has an audit result.
+3. Present each failed item via the `jsc-ask:ask` decision tree (apply the proposed fix / skip / custom fix). Every option states its impact scope (example: skipping leaves the skill non-compliant until the next audit). Completion condition: every finding has a recorded decision.
+4. Apply the confirmed fixes — this step MUST run as a sub agent, one sub agent per affected domain repo: modify the files, sync that domain README's 「Skills 目錄」 section, and bump the version in all three manifests. Completion condition: every affected repo carries the fixes and the manifest bump.
+5. Re-check the guidelines.md audit checklist for every touched skill. On any failure, **return to step 3**: confirm and fix again, until all items pass. Completion condition: all checklist items pass.
+6. Call `jsc-git:pr` once per affected domain repo to open a Push Request. Completion condition: every affected repo has a PR URL.