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/implement/SKILL.md

@@ -11,7 +11,7 @@ Goal: complete the analysis page's todos one by one; **update the wiki status im
 
 **Content pages and directory pages live in different wiki repos.** `ANALYZE_{HASH}` sits in the repo `jsc-gitea/tools/gitea.sh wiki-repo ANALYZE` resolves and `DELIVER_{HASH}` in the one `gitea.sh wiki-repo DELIVER` resolves, while the directory pages `ANALYZE_CONTENTS`, `DELIVER_CONTENTS` and `MAINTAIN_CONTENTS` all sit in the repo `gitea.sh wiki-repo CONTENTS` resolves: `JSC_WIKI_REPO_CONTENTS` first, `JSC_WIKI_REPO` second, exit 3 when neither is set; it **never** falls back to the page type's own variable. Every directory row links its content page by the absolute URL from `gitea.sh wiki-url {content repo} {page}`, written as `[{text}]({url})` — one link syntax, whichever wiki the two pages sit in. The syntax and the check that runs before every write: "Every link is checked before it reaches a page" below.
 
-All wiki reads and writes go through `jsc-gitea:wiki`. **A failed wiki read or write stops this stage**: report which page and which operation failed, never carry on against a page you could not read, and never report a page as saved when the write failed. Step 13 still runs after such a stop.
+All wiki reads and writes go through `jsc-gitea:wiki`. **A failed wiki read or write stops this stage**: report which page and which operation failed, never carry on against a page you could not read, and never report a page as saved when the write failed. Steps 13 and 14 still run after such a stop.
 
 ## Steps
 
@@ -97,6 +97,21 @@ All wiki reads and writes go through `jsc-gitea:wiki`. **A failed wiki read or w
     - `--worktree {path} --source-branch {name} --work-branch {name} --pr {url}` — the script reads the commit count, the push state and whether the source branch exists on the remote by itself, so pass the names, not your own count.
 
     Rules and exit codes: `references/stage-report.md`. Exit 1 is a warning, never a block. Completion condition: the script's output is reported to the user verbatim, and it names the worktree, all three branches and every wiki page this run wrote.
+14. **Write this run's `skill-end` status event — the very last thing this stage does, right after step 13, on every path including every early stop.** Run `jsc-hooks/tools/report-status.sh skill-end jsc-sdlc:implement {status} {exit} [detail]`, naming the script the way this stage already names `jsc-hooks/hooks/sdlc-gate.sh` in step 1. The matching `skill-start` event is written by jsc-hooks on its own, so this step owes only the `end`: a hook fires on the skill tool call and this stage's work happens in the model turns after it, so **no hook can see how this run ended**. A `start` with no `end` is what an aborted run looks like in the record, and this stage is the one that most often runs for hours before it stops, so the missing `end` is exactly the case worth telling apart.
+
+    `{status}` is one of five words, never a sixth:
+
+    | Status | When `implement` reports it |
+    | --- | --- |
+    | `ok` | Every step's completion condition is met: the gate passed, the claimed package's todos all show `[x]`, both closing audits cleared (a reported API-document skip counts as cleared), `pr-watch.sh` returned 0 with `wp-gate.sh check` reporting `status=merged`, the work log entries are saved, the delivery was produced, the maintenance question was answered, and `tools/stage-report.sh` exited 0 |
+    | `blocked` | A gate stopped this run before any package was worked on: `sdlc-gate.sh lock implement` exited non-zero because the model carries no `coding` tag, every candidate came back `status=blocked` from `wp-gate.sh check-deps` because a dependency's PR is not merged, `wp-gate.sh owns` answered `status=foreign` on the only PR left to settle, or the analysis page's source branch is missing from the remote (step 5.3). No code was written. Comment rounds that step 2 did finish are named in `[detail]`, because they are real work sitting behind a blocked verdict — but they do not turn it into `ok` |
+    | `failed` | Work started and then something did not complete: a `wp-gate.sh` call returned 3 (`status=missing-dep`, a gate that could not decide), `pr-watch.sh` returned 2 or 3, `wp-gate.sh check` reported `status=closed-unmerged`, an audit could not be brought to a passing verdict, or a wiki write did not land (`wiki-url` 5, 7 or 8; `link-check.sh` 1; `wiki-contents.sh` 1, 7 or 8) |
+    | `degraded` | The package itself finished — todos `[x]`, PR merged — but a closing item did not: `DELIVER_{HASH}` is saved while `DELIVER_CONTENTS` was not upserted, the maintenance registration went unrecorded on `wiki-contents.sh` exit 3, or `tools/stage-report.sh` exited 1 (no work log, or a link in its list does not answer) |
+    | `aborted` | The user stopped the run, or the run stopped itself because its premise did not hold — step 3 found no selectable work package, so there was nothing to implement |
+
+    `{exit}` is the exit code of the script whose verdict decided the status — the gate's code for `blocked`, the failing script's code for `failed` and `degraded` — and `0` when nothing exited non-zero, `ok` and `aborted` included. `[detail]` is optional and Traditional Chinese per the STE100 rule: one line, no line break, naming what decided the status (for example 「相依工作包的 PR 未合併」 or 「交付目錄列未寫入」). The script truncates it at 200 characters, so put the short reason there and nothing else.
+
+    **A failure in this step never changes this stage's verdict.** The script is not found (jsc-hooks is not installed on this machine, or this CLI's layout puts it somewhere else) → skip the event quietly and carry on; nothing is reported to the user and no step is re-run. The three recording sub-commands are built to exit 0 even when the write fails, so a non-zero code here means only that the call itself was malformed (exit 2, a usage error) — fix the arguments once and, either way, never turn a merged work package into a failed stage because the record of it failed. Completion condition: one `skill-end` event has been written for this run, or the script could not be found and that skip is the reason no event exists.
 
 ## Every link is checked before it reaches a page