feat(link): 連結一律寫成 [文字](絕對網址)，寫入前先驗證連得到

取消 [[頁名]] 與 [[顯示文字|頁名]] 兩種同 wiki 寫法，不再分「同存取庫」與
「跨存取庫」兩條規則。那種寫法只在自己那個 wiki 內解析，寫錯不報錯，畫面上
看起來像普通文字或死連結，巡不到也修不了。

連結寫進頁面前先過 jsc-gitea 的 link-check.sh，結束碼 0 才寫。驗證一律走 API，
不看網頁狀態碼：私有存取庫的網頁網址對未登入請求一律回 404，拿狀態碼判會把
好連結判成壞的。認證失敗回 7，與死連結的 1 分開，免得金鑰一過期就把還在的頁
整批判死。

skills/skill-update/SKILL.md

@@ -20,11 +20,12 @@ Single source of guidelines: [`../../references/guidelines.md`](../../references
    1. Follow [`../../references/deploy-verify.md`](../../references/deploy-verify.md) from section 1 to section 5: `tools/deploy-route.sh {domain-path}` picks the route, the deploy route or the worktree route runs, and the verification then runs in a **fresh CLI process**, never in the session that ran the deploy. That session raised the restart gate itself and still holds the old skill body, so verifying inside it either gets blocked or passes on stale behavior. Verify the updated `description` in the skill's `tools/list-skills.sh` row, every tool this change touched, and one minimal prompt per checkable CLI — the per-CLI prompts run in parallel. Completion condition: every completion condition in `deploy-verify.md` sections 1 to 5 holds for this domain repo.
    2. Write the change report to the wiki — this part MUST run as a sub agent. It is two pages in two repos, and they must not be mixed up.
       - **Content page `SKILLSET_{HASH}`.** Resolve its repo with `jsc-gitea/tools/gitea.sh wiki-repo SKILLSET`, which reads `JSC_WIKI_REPO_SKILLSET` first, then `JSC_WIKI_REPO`. `{HASH}` is `gitea.sh hash-id "{owner}/{repo}"` of the changed domain repo, used at the full 40 characters it prints. Write it through `jsc-gitea:wiki` following [`../../templates/skillset-page.md`](../../templates/skillset-page.md): **append** a section for this change — date, 「更新」, skill name, changed files, PR URL, the step 8.1 route verdict and verification result per item — and keep every earlier section.
-      - **Directory page `SKILLSET_CONTENTS`.** It lives in the CONTENTS repo, never in the SKILLSET one. `wiki-contents.sh` resolves it itself with `gitea.sh wiki-repo CONTENTS`, whose chain is `JSC_WIKI_REPO_CONTENTS` then `JSC_WIKI_REPO` and never falls back to `JSC_WIKI_REPO_SKILLSET`. Build one file holding the single row from [`../../templates/skillset-contents.md`](../../templates/skillset-contents.md), its 異動頁 cell carrying the **absolute** URL from `gitea.sh wiki-url {SKILLSET repo} SKILLSET_{HASH}` — `[[SKILLSET_{HASH}]]` resolves only inside the directory page's own wiki, so it would be a dead link. Then run:
+      - **Directory page `SKILLSET_CONTENTS`.** It lives in the CONTENTS repo, never in the SKILLSET one. `wiki-contents.sh` resolves it itself with `gitea.sh wiki-repo CONTENTS`, whose chain is `JSC_WIKI_REPO_CONTENTS` then `JSC_WIKI_REPO` and never falls back to `JSC_WIKI_REPO_SKILLSET`. Build one file holding the single row from [`../../templates/skillset-contents.md`](../../templates/skillset-contents.md), its 異動頁 cell written as `[SKILLSET_{HASH}]({url})` with the **absolute** URL from `gitea.sh wiki-url {SKILLSET repo} SKILLSET_{HASH}`. Every link on both pages takes that `[{text}]({url})` form; the double-bracket wiki-link form resolves only inside one wiki, so it is never used. Then run:
 
         `jsc-gitea/tools/wiki-contents.sh upsert SKILLSET 2 "{owner}/{repo}" {row file} templates/skillset-contents.md`
 
         The key column is `2`, the 存取庫 column, holding that repo's `{owner}/{repo}` exactly as the row file writes it, so one domain keeps exactly one row and no other domain's row moves. Never hand-edit the directory page. Write the content page first and fetch the URL only after it exists.
+      - **Check the links before writing.** Hand every URL going onto the content page and into the directory row to `jsc-gitea/tools/link-check.sh`, and write only when it exits 0. It verifies through the Gitea API, never a web status code: a private repo answers 404 to an unauthenticated web request, so a status-code check would call a live page dead.
       - **Exit codes.** Route every one of them:
 
         | Call | Exit | Do |
@@ -38,6 +39,11 @@ Single source of guidelines: [`../../references/guidelines.md`](../../references
         | | 7 or 8 | Stop and write nothing: a page rebuilt on top of an unread read loses every section already on it |
         | `gitea.sh wiki-url` | 4 | The content page is not there, so the write above did **not** succeed. Go back and write it, and add no directory row until the page exists |
         | | 5 | The API answered with no `html_url`. Stop and report it; never assemble the URL by hand from the host and the page name |
+        | `link-check.sh` | 0 | Every link is reachable. Write the page |
+        | | 1 | At least one link is dead. Write nothing, and report the `DEAD` lines it printed |
+        | | 2 | No URL was passed, which is a defect here. Pass the links and rerun |
+        | | 3 | `GITEA_HOST` is unset. Set it and rerun; never skip the check instead |
+        | | 7 | Gitea authentication failed. Stop and report the key problem, and never read it as a dead link |
         | `wiki-contents.sh upsert` | 0 | The row is in place. Report the `updated` or `added` it printed |
         | | 1 | The write failed. Report `SKILLSET_CONTENTS` as not written, together with the row content |
         | | 2 | An argument was rejected. Fix it and rerun; nothing was written |