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/ask/SKILL.md

@@ -43,3 +43,7 @@ Inside one work session this skill is the only writer of `QUESTION_{HASH}` and `
    - Branch on `wiki-contents.sh`'s exit code, every code its own branch. 0: the row was added or updated, so this round is recorded. 1: the write failed, so retry once per step 3. 2: usage error, so stop and report the arguments that were passed — the same call retried fails the same way. A template path that does not exist lands here too, and means the plugin installation is incomplete. 3: no `CONTENTS` repo is configured, so report that `JSC_WIKI_REPO_CONTENTS` (or `JSC_WIKI_REPO`) must be set, note `QUESTION_{HASH}` as written but unindexed, and hand this round's answers back to the calling skill all the same. **Never withhold the answers over this code.** `JSC_WIKI_REPO_CONTENTS` is a `fix=ask` item in `jsc-cli/tools/config-spec.tsv`, so `/jsc-cli:setup` can only learn its value by asking through this skill; an answer dropped here leaves the variable unset, and the unset variable makes the next round drop the answer again. 4: the page does not exist and no template reached the script. The call form above always passes the template as the fifth argument, so this code cannot come out of it — getting it means that argument was dropped, so restore it and run the same call once more. 7: the key is invalid or has no permission, so stop and report without retrying. 8: any other API failure, so retry once per step 3, then stop and report.
    - Done when the sub agent has reported both writes as succeeded and the main agent has accepted that one report — this single confirmation covers both pages and both templates; do not re-read the pages to prove it. Exit 2, 3 or 7 from `wiki-contents.sh`, any `wiki-url` failure, and any non-zero `link-check.sh` exit on the directory row, close this step the second way: `QUESTION_{HASH}` counts as written and unindexed, the report names the exit code and the page that stayed unwritten, and this round's answers go back to the calling skill regardless. **The answers of a finished questioning round are never lost because the directory page could not be written.**
 3. On a reported write failure, retry that one page once — a `QUESTION_{HASH}` failure, or `wiki-contents.sh` exit 1 or 8. Exit 2, 3 and 7 are not retried, because the same call fails identically until someone fixes the arguments, the environment or the key; they end the recording, not the round. Every one of these paths ends the same way: the answers go back to the calling skill, and the report names the page that stayed unwritten, the exit code behind it, and what was recorded and what was not. Done when the retry succeeded and step 3 of "Session cache" refreshed that page's copy, or — when the retry also failed, or the code was 2, 3 or 7 — the report above has been printed and the answers have been handed back.
+4. Record how this run ended. This is the closing step and it runs on every route above, the ones that stopped early included. Run `jsc-hooks/tools/report-status.sh skill-end jsc-ask:ask {status} {exit} "{detail}"`, resolving the script the same sibling-plugin way this skill already resolves `jsc-gitea/tools/hash-id`. The hook that records a skill's start cannot see how it ended — it fires when the skill is loaded, and the work happens in later turns — so a start with no matching end is exactly what an abandoned run looks like, and writing this line is what keeps a finished run from reading as one.
+   - `{status}` is one of five. `ok`: every question of this round carries an answer, the answers went back to the calling skill, and where `{owner}/{repo}` was known both wiki pages were written. `degraded`: the round finished and part of the recording did not — no `{owner}/{repo}` was known so nothing was recorded at all, or `QUESTION_{HASH}` landed while `QUESTION_CONTENTS` did not (`wiki-contents.sh` exit 2, 3 or 7, any `wiki-url` failure, or a non-zero `link-check.sh` on the directory row). Those stay `degraded` rather than `failed` because the answers still reached the caller, which is this skill's own completion condition. `aborted`: the user stopped the questioning round, so the undecided points were never put to them. `failed`: the run stopped and no answers came back — `hash-id` found no SHA-1 helper, a wiki read failed with anything other than exit 4, or the one retry of a page write failed as well. `blocked` does not arise here, because anything that gates this skill stops it before it ever reaches this step.
+   - `{exit}` is the exit code of the tool that decided the outcome where one did, and otherwise 0 for `ok` and 1 for every other status. `{detail}` is optional, one line, at most 200 characters: name the page that stayed unwritten, or the tool and the code that stopped the run. Anything longer belongs in the report to the caller, not on this line.
+   - Reporting never changes the outcome of the round. `report-status.sh` is not on every machine, so a missing file is skipped in silence and nothing else about the run changes; the script swallows its own write failures and always exits 0, so its result is never worth branching on. Done when the call was made, or the script was absent and this step was skipped without a word.