feat(skills): 新增技能详情字段并统一发布图标

- 技能新增 detail 字段(skills 表新增列 + Alembic 迁移),
  由管理员或技能发布者编辑,内置/公开技能仅管理员可编辑
- 新增 PUT /api/skills/{name}/detail 接口,GET/列表接口返回 detail
- 新增可复用的技能详情弹窗组件,支持 Markdown 渲染与内联编辑
- 智能体创建/编辑选技能、智能体卡片技能徽章均可查看技能详情
- 将定时任务/智能体/技能的发布图标统一为 Globe/Lock

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

offline-backend-20260512/backend/CLAUDE.md

@@ -214,7 +214,7 @@ FastAPI application on port 8001 with health check at `GET /health`. Set `GATEWA
 |--------|-----------|
 | **Models** (`/api/models`) | `GET /` - list models; `GET /{name}` - model details |
 | **MCP** (`/api/mcp`) | `GET /config` - get config; `PUT /config` - update config (saves to extensions_config.json) |
-| **Skills** (`/api/skills`) | `GET /` - list skills (optional `search` fuzzy-name + `tag_id` filters; each item carries `tags`); `GET /{name}` - details; `PUT /{name}` - update enabled; `POST /install` - install from .skill archive (accepts standard optional frontmatter like `version`, `author`, `compatibility`) |
+| **Skills** (`/api/skills`) | `GET /` - list skills (optional `search` fuzzy-name + `tag_id` filters; each item carries `tags` + owner-authored `detail`); `GET /{name}` - details; `PUT /{name}` - update enabled; `PUT /{name}/detail` - set the long-form `detail` text (custom skill: owner or admin; built-in/public: admin only — materializes a `skills` row on demand); `POST /install` - install from .skill archive (accepts standard optional frontmatter like `version`, `author`, `compatibility`) |
 | **Memory** (`/api/memory`) | `GET /` - memory data; `POST /reload` - force reload; `GET /config` - config; `GET /status` - config + data |
 | **Agents** (`/api/agents`) | `GET /` - list built-in, owned, and published agents (optional `search` + `tag_id` filters; each item carries `tags`); `POST /` - create user-owned agent; `GET/PUT/DELETE /{id}` - read/update/delete by stable agent id; `GET /check` - validate non-empty display name (duplicates allowed) |
 | **Tags** (`/api/tags`) | `GET /` - list tags (optional `tag_type` filter; open to all); `POST /` - create tag (admin); `PUT /{id}` / `DELETE /{id}` - update/delete tag (admin); `GET /assignments/{target_type}/{target_id}` - tags on a resource; `PUT /assignments/{target_type}/{target_id}` - replace a resource's tags (admin). Tags are typed `agent`/`skill`/`scheduled_task` and may only tag resources of their own type. |