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-delete/SKILL.md

@@ -36,11 +36,12 @@ Single source of guidelines: [`../../references/guidelines.md`](../../references
       On any mismatch — the deleted skill still listed, a leftover from exit 1, a fixed caller that now fails, a prompt failure, or unexpected stderr — fix the cause and rerun this step from 8.1. Completion condition: the skill is absent from the list, the verification script exits 0 or its exit 3 is reported as「無處可查」and carried into step 8.3, every fixed caller ran, every checkable CLI completed the prompt with the expected result, and every untestable CLI has a stated reason.
    3. 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 domain repo that lost the skill, 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, 「刪除」, skill name, changed files (the step 5 inventory verdicts included), PR URL, the step 8.1 route verdict and the step 8.2 verification result per item, the deep-delete verdict「無處可查」included when it applies — 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 |
@@ -54,6 +55,11 @@ 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 |