新增 update-triage SKILL，以及对应的 Github Workflow，解决 triage issue 的仓库级别 SKILL 的自进化

[Terry-Mao]

update-triage 是一个 triage 自我改进流程：从最近被 triage 过的 issue 里收集 maintainer 的后续修正信号，然后把稳定、重复的模式沉淀到 repo-local triage 规则里。

它主要更新：

• .agents/skills/triage-issue-repo/SKILL.md
• 必要时更新 .github/issue-triage/config.json

不会改：

• .agents/skills/triage-issue/SKILL.md
• .agents/skills/dedupe-issue-repo/SKILL.md
• 其他 core skill

流程大概是：

1. 确认 gh auth status 可用。
2. 跑聚合脚本：

python3 .agents/srcipts/aggregate_triage_feedback.py

3. 脚本默认看最近 7 天，找带 triaged label 且最近有更新的 issue。

4. 对这些 issue 收集：

   • 后续 label 变更：labeled / unlabeled
   • reopened
   • maintainer 后续评论

5. 明确排除 closed-as-duplicate 信号，因为那归 update-dedupe。

6. 读脚本输出的 JSON，找重复模式，比如：

   • maintainer 总是把某类 issue 从 bug 改成 enhancement
   • maintainer 总是在某类 issue 里问同样的问题
   • Bot 总是推断错某类 issue 的分类/owner

7. 如果证据足够，就最小化修改 triage-issue-repo，必要时改 label config。

8. 如果只是单个 one-off override，不更新规则。

9. 最后要求提交到本地分支 feat/update-triage，入口脚本会做 write-surface guard，通过后才 push/open PR。

核心原则是：只把 maintainer 反复纠正出来的 repo-specific 经验写进 local companion skill，不动跨仓库 core triage contract。

[github-actions]

Triage Summary

This is an enhancement request to add an update-triage self-evolution flow for repository-specific issue triage guidance.

Evidence from the repo shows the current triage path uses .agents/skills/triage-issue/SKILL.md, .agents/skills/triage-issue-repo/SKILL.md, and .github/workflows/triage-issue.yml. The repo also already has analogous self-evolution workflows for dedupe and PR review guidance via update-dedupe and update-pr-review.

Suggested labels: documentation, enhancement, repro:high, triaged, area:workflow, area:skills.

Duplicate check: no duplicate found. Existing issues for update-dedupe and update-pr-review are related precedents, but they target different companion skills.

[github-actions]

Implementation status for issue #134: ready for review.

Review the implementation changes in the PR. Complete any manual verification needed before merging.

Pull request: #254