feat: 迁移统一目录元数据契约 (#102)

## 中文

- 为 System Agent、34 个 Builtin Skill、28 个 Pointer/Collection 条目增加 catalog
sidecar
- 覆盖 147 个 collection child，并固定可证明的来源；无法证明的内容保持 listing-only/unknown
- 增加 strict Schema、validator、collection check 与 CI 完整性门禁

## English

- Add catalog metadata sidecars for the System Agent, 34 built-in
Skills, and 28 pointer/collection entries
- Cover 147 collection children while keeping unverifiable facts
listing-only or unknown
- Add strict schemas, validators, deterministic collection checks, and
CI completeness gates

## 验证 / Verification

- Catalog validator 17/17
- Collection generator 4/4
- 63 sidecars, 147 children, zero errors

skills/amap-jsapi-skill/entry.json

@@ -27,6 +27,7 @@
   "redistribution": "allowed",
   "source": {
     "kind": "web",
-    "repoUrl": "https://clawhub.ai/api/v1/skills/amap-jsapi-skill/file?path=SKILL.md&ownerHandle=lbs-amap"
+    "repoUrl": "https://clawhub.ai/api/v1/skills/amap-jsapi-skill/file?path=SKILL.md&ownerHandle=lbs-amap",
+    "sha256": "cf2f06cc5abf5e41a626f823c50575ab52c81aecbceca5abd4e69d56ca5c5d75"
   }
 }