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/update-agent/catalog-metadata.v1.json

@@ -0,0 +1,73 @@
+{
+  "$schema": "../../schemas/catalog-metadata.v1.schema.json",
+  "schemaVersion": 1,
+  "identity": {
+    "kind": "skill",
+    "id": "update-agent"
+  },
+  "presentation": {
+    "defaultLocale": "en-US",
+    "i18n": {
+      "zh-CN": {
+        "name": "更新智能体",
+        "summary": "安全更新智能体配置、人格、规则与技能，支持 diff 预览与版本回滚",
+        "description": "安全更新现有智能体的配置、人格、原则、技能与记忆，输出可审阅 diff 并在确认后应用与提交。Use when 用户要求修改 Agent 行为、安装/卸载技能、调整配置、回滚变更或修订规则。"
+      },
+      "en-US": {
+        "name": "Update Agent",
+        "summary": "Safely update Agent config, persona, principles, and skills, with diff preview and version rollback",
+        "description": "Safely update an existing Agent's config, persona, principles, skills, and memory, producing reviewable diffs that are applied and committed only after confirmation. Use when the user asks to modify Agent behavior, install/uninstall skills, adjust config, roll back changes, or revise rules."
+      }
+    },
+    "category": "productivity",
+    "tags": [
+      "agent",
+      "update",
+      "meta"
+    ]
+  },
+  "release": {
+    "state": "known",
+    "version": "3.2.1",
+    "versionScheme": "semver"
+  },
+  "timestamps": {
+    "catalogUpdatedAt": {
+      "state": "known",
+      "value": "2026-08-25T09:25:42Z",
+      "precision": "second"
+    },
+    "releasePublishedAt": {
+      "state": "unknown"
+    },
+    "reviewedAt": {
+      "state": "unknown"
+    },
+    "upstreamObservedAt": {
+      "state": "unknown"
+    }
+  },
+  "provenance": {},
+  "governance": {
+    "stewardship": "official",
+    "availability": "installable",
+    "license": {
+      "state": "unknown"
+    },
+    "redistribution": "verify-package-terms",
+    "listingMaintainer": {
+      "name": "DesireCore Official",
+      "verified": true
+    }
+  },
+  "compatibility": {
+    "platforms": {
+      "state": "unknown"
+    },
+    "requiredClientVersion": "10.0.108"
+  },
+  "spec": {
+    "kind": "skill",
+    "riskLevel": "low"
+  }
+}