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

@@ -0,0 +1,73 @@
+{
+  "$schema": "../../schemas/catalog-metadata.v1.schema.json",
+  "schemaVersion": 1,
+  "identity": {
+    "kind": "skill",
+    "id": "delete-agent"
+  },
+  "presentation": {
+    "defaultLocale": "en-US",
+    "i18n": {
+      "zh-CN": {
+        "name": "删除智能体",
+        "summary": "安全删除智能体及其关联数据，支持多重确认与可选历史清理",
+        "description": "安全删除指定的智能体及其关联数据。删除前会验证智能体状态，支持可选地删除所有会话历史。Use when 用户需要删除不再使用的智能体。"
+      },
+      "en-US": {
+        "name": "Delete Agent",
+        "summary": "Safely delete an Agent and its associated data, with multi-step confirmation and optional history cleanup",
+        "description": "Safely delete a specified Agent and its associated data. Verifies the Agent's state before deletion and optionally removes all session history. Use when the user needs to delete an Agent that is no longer in use."
+      }
+    },
+    "category": "productivity",
+    "tags": [
+      "agent",
+      "deletion",
+      "meta"
+    ]
+  },
+  "release": {
+    "state": "known",
+    "version": "2.6.0",
+    "versionScheme": "semver"
+  },
+  "timestamps": {
+    "catalogUpdatedAt": {
+      "state": "known",
+      "value": "2026-08-25T08:13:09Z",
+      "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": "10.0.90"
+  },
+  "spec": {
+    "kind": "skill",
+    "riskLevel": "high"
+  }
+}