feat(skill): beta 技能 diagnosing-bugs + 月度审阅与 evals 工具

- 新增 diagnosing-bugs（beta）：先建红循环再推理、二分定位、补回归测试；含 evals 与四段式文档
- 路由表加入难查 bug 行
- scripts/monthly-review.sh：一条命令跑月度审阅
- scripts/evals-status.py + reports/evals/TEMPLATE.md：evals 覆盖与回归报告模板
- skill-creator 实战记录 #1（待观察后晋升）

catalog.json

@@ -7,13 +7,14 @@
     "missing_evals": [],
     "missing_docs": []
   },
-  "generated_at": "2026-10-31T21:19:23Z",
-  "total": 61,
+  "generated_at": "2026-10-31T21:33:50Z",
+  "total": 62,
   "counts": {
     "promoted/user-invoked": 18,
     "deprecated/user-invoked": 1,
     "promoted/model-invoked": 40,
     "beta/user-invoked": 1,
+    "beta/model-invoked": 1,
     "deprecated/model-invoked": 1
   },
   "skills": [
@@ -420,6 +421,19 @@
       "has_evals": true,
       "has_docs": true
     },
+    {
+      "name": "diagnosing-bugs",
+      "category": "dev",
+      "version": "0.1.0",
+      "status": "beta",
+      "invocation": "model-invoked",
+      "description": "难查 bug 的诊断纪律：先造出一条「现在就为这个 bug 变红」的紧反馈循环，再二分定位、最小验证、补回归测试。当 bug 难复现、间歇失败、或第一次看没头绪时使用。",
+      "description_len": 84,
+      "path": "skills-dev/diagnosing-bugs-plugin/skills/SKILL.md",
+      "digest": "d93fb95c073858cc",
+      "has_evals": true,
+      "has_docs": true
+    },
     {
       "name": "executing-plans",
       "category": "dev",