feat(shop): 商品管理编辑弹窗替换为WangEditor富文本编辑器

- 用户反馈编辑弹窗的Markdown编辑器体验差，采用website-admin的富文本编辑器替代
- 新增依赖@wangeditor/editor、@wangeditor/editor-for-vue、markdown-it及类型声明
- 新建RichTextEditor组件，去除Nuxt专用包装，适配现有文件上传接口
- shopGoodsEdit.vue移除MdEditor及相关冗余代码，改用RichTextEditor显示内容
- 实现编辑时Markdown内容转换为HTML，保持数据库存储格式新旧兼容
- 保存逻辑保持不变，提交内容为HTML格式
- 确认小程序端可兼容新旧内容格式，潜在HTML图片链接误解析风险
- build验证通过，文件产出正常，图片上传小程序域名白名单需上线后确认

package.json

@@ -32,6 +32,8 @@
     "@bytemd/plugin-gfm": "^1.17.2",
     "@bytemd/plugin-highlight": "^1.17.4",
     "@bytemd/plugin-highlight-ssr": "^1.20.2",
+    "@wangeditor/editor": "^5",
+    "@wangeditor/editor-for-vue": "^5",
     "@wecom/jssdk": "^1.3.1",
     "ali-oss": "^6.18.0",
     "ant-design-vue": "^4.2.6",
@@ -53,6 +55,7 @@
     "js-md5": "^0.7.3",
     "jsbarcode": "^3.11.5",
     "lodash-es": "^4.17.21",
+    "markdown-it": "^14",
     "md-editor-v3": "^5.2.3",
     "mitt": "^3.0.1",
     "nprogress": "^0.2.0",
@@ -73,6 +76,7 @@
     "@types/dompurify": "^3.2.0",
     "@types/file-saver": "^2.0.7",
     "@types/lodash-es": "^4.17.6",
+    "@types/markdown-it": "^14.1.2",
     "@types/node": "^22.15.0",
     "@types/nprogress": "^0.2.0",
     "@types/qrcode": "^1.5.5",