feat(狀態回報): 收尾寫一筆 skill-end 事件

現行紀錄只記「被叫用」，沒有成敗也沒有結束碼。跑完整輪的技能與開場就
中止的技能，在紀錄裡長得一模一樣。

start 由技能用量 hook 順手發，不必改技能文件。end 只能由技能自己在收尾
步驟寫——hook 接在技能工具呼叫上，而實際工作發生在之後的模型輪次，它在
原理上看不到成敗。有 start 沒有配對的 end，就是那一輪中止了。

status 五選一，每支技能各自寫明什麼情況選哪一個。找不到回報腳本就安靜
跳過，回報失敗一律不改變技能自己的結論。

skills/commit/SKILL.md

@@ -24,6 +24,23 @@ description: 'Group all pending file changes by conventional type and feature, t
      - Exit 4 (API call failed) → report the failure and leave the PR state as unknown. Never read a failed call as "no open PR": that leaves a stale title on a branch that just gained commits.
      - Any other non-zero → treat it as exit 4.
    - Done when the report states exactly one of these: the lookup was skipped because `jsc-git:pr` called this run, the branch has no open PR, `jsc-git:pr` reported each of the three items as matched or updated, or the lookup failed and the failure is named.
+6. Record how this run ended, as the very last thing this skill does:
+
+   `jsc-hooks/tools/report-status.sh skill-end jsc-git:commit {status} {exit} "{detail}"`
+
+   Resolve that path the way step 2 already resolves `jsc-hooks/hooks/comment-scope.sh` — the sibling plugin directory, no separate lookup rule for this one call. **A missing script is not a failure here: skip this step in silence and let the run end as it stands**, the same way step 2 commits anyway when the sweep is not installed. The script swallows its own write errors and exits 0 even then, so nothing branches on its code either. Commits that landed stay landed whether or not the run could be recorded.
+
+   | status | This skill's case |
+   | --- | --- |
+   | `ok` | Every group is committed, `git status --porcelain` prints nothing, and step 5 stated one of its four outcomes. A step 2 sweep that was skipped because the script is not on this machine is still `ok` — say so in `{detail}`, since a run judged without the sweep is worth telling apart from one the sweep passed |
+   | `blocked` | The `jsc-hooks` PreToolUse `Bash` guard rejected the commit before git ran — a bulk `git add -A` pair, or a message carrying no Traditional Chinese — so no commit landed and the working tree is exactly as it was |
+   | `degraded` | Every group is committed and the tree is clean, but the close-out is short: step 5's `pr-of-branch` returned 4, or the `jsc-git:pr` calibration failed, so the open PR still carries a title written before these commits |
+   | `failed` | A `git add` or `git commit` returned non-zero part-way through, leaving some groups committed and the tree dirty. Report the group that broke; a partial commit set is what the next run has to reconcile |
+   | `aborted` | Step 1's inventory came back empty, so there was nothing to commit and nothing was attempted. Also the user stopping the run at the grouping or the message-style question. This is not a success: a run that committed nothing must not read like a run that committed everything |
+
+   `{exit}` is the exit code of whatever decided the status, `0` for `ok`. `{detail}` is one short line well under 200 characters: group and commit counts plus exit codes, never commit messages, branch names, or personal data.
+
+   Done when the command has run, or the script was absent and this step was skipped.
 
 ## Type table