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/mail-operations/catalog-metadata.v1.json

@@ -0,0 +1,76 @@
+{
+  "$schema": "../../schemas/catalog-metadata.v1.schema.json",
+  "schemaVersion": 1,
+  "identity": {
+    "kind": "skill",
+    "id": "mail-operations"
+  },
+  "presentation": {
+    "defaultLocale": "en-US",
+    "i18n": {
+      "zh-CN": {
+        "name": "邮箱操作",
+        "summary": "邮件收发、搜索、标签管理、自动规则与智能体邮件处理",
+        "description": "Use this skill whenever the user wants to interact with email. This includes reading inbox, sending emails, replying, searching messages, managing labels and categories, downloading attachments, setting up auto-reply rules, or triggering agents to handle incoming emails. Supports Gmail, Outlook, and IMAP/SMTP (QQ Mail, 163, Yahoo, etc.) through DesireCore's local REST API. Use when 用户提到 邮件、邮箱、收件箱、发邮件、回复邮件、查邮件、Gmail、 Outlook、QQ邮箱、163邮箱、附件、标签、草稿、自动回复、邮件规则、 转发、抄送、未读邮件、收信、发信、邮件同步、邮件搜索。"
+      },
+      "en-US": {
+        "name": "Email Operations",
+        "summary": "Email send/receive, search, label management, auto-rules, and Agent-driven email handling",
+        "description": "Use this skill whenever the user wants to interact with email. This includes reading inbox, sending emails, replying, searching messages, managing labels and categories, downloading attachments, setting up auto-reply rules, or triggering agents to handle incoming emails. Supports Gmail, Outlook, and IMAP/SMTP (QQ Mail, 163, Yahoo, etc.) through DesireCore's local REST API. Use when the user mentions email, mailbox, inbox, sending email, replying, checking email, Gmail, Outlook, QQ Mail, 163 Mail, attachments, labels, drafts, auto-reply, email rules, forwarding, CC, unread email, receiving, sending, email sync, or email search."
+      }
+    },
+    "category": "productivity",
+    "tags": [
+      "mail",
+      "email",
+      "gmail",
+      "outlook",
+      "imap",
+      "smtp"
+    ]
+  },
+  "release": {
+    "state": "known",
+    "version": "1.0.5",
+    "versionScheme": "semver"
+  },
+  "timestamps": {
+    "catalogUpdatedAt": {
+      "state": "known",
+      "value": "2026-07-07T13:14:31Z",
+      "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"
+    }
+  },
+  "spec": {
+    "kind": "skill",
+    "riskLevel": "medium",
+    "skillType": "procedural"
+  }
+}