feat(admin): 公众号式写文章富文本编辑器(WangEditor) + OSS 上传

- 新增 @wangeditor/editor(+for-react)/dompurify；/article-editor 整页编辑器：左侧封面/标题/新建内容，顶部 WangEditor 工具栏(图片/视频/超链接走 /admin/upload)，中央标题(0/64)+作者+富文本正文，底部字数/保存草稿/预览/发表
- contentApi +getOne；后端 GET /content/{id} 回填
- 资讯列表「写文章」header + 每行「编辑文章」跳转编辑器；CrudTable +headerActions/createLabel
- 预览用 DOMPurify 消毒富文本

Co-Authored-By: Claude <noreply@anthropic.com>

package.json

@@ -11,8 +11,11 @@
   },
   "dependencies": {
     "@rc-component/qrcode": "^2.0.0",
+    "@wangeditor/editor": "^5.1.23",
+    "@wangeditor/editor-for-react": "^1.0.6",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "dompurify": "^3.4.14",
     "lucide-react": "^0.468.0",
     "radix-ui": "^1.4.3",
     "react": "^18.3.1",