feat: 品牌裁剪弹窗/Markdown 行内短代码与详情视频块等

新增：
- BrandCropModal 品牌图裁剪弹窗 + cropImage 工具
- Markdown 行内短代码（inlineShortcodes + remark 插件）
- MdDetails 折叠块、MdVideo 视频块组件
- directiveBlocks/inlineShortcodes 测试

其它：
- 聊天后端（handler/service chat）调整
- Markdown 渲染链路、编辑器、全局样式与品牌相关面板更新

frontend/package.json

@@ -9,7 +9,7 @@
     "postbuild": "node scripts/extract-font-css.mjs",
     "start": "next start -p 3000",
     "lint": "next lint",
-    "test": "node --experimental-strip-types --test lib/siteUrl.test.ts lib/jsonLd.test.ts lib/urlStyle.test.ts lib/mobileTabs.test.ts lib/headerNav.test.ts lib/widgetCode.test.ts lib/widgetLint.test.ts lib/smartDiff.test.ts lib/dyEmoji.test.ts lib/entryBlocks.test.ts lib/bookSearch.test.ts"
+    "test": "node --experimental-strip-types --test lib/siteUrl.test.ts lib/jsonLd.test.ts lib/urlStyle.test.ts lib/mobileTabs.test.ts lib/headerNav.test.ts lib/widgetCode.test.ts lib/widgetLint.test.ts lib/smartDiff.test.ts lib/dyEmoji.test.ts lib/entryBlocks.test.ts lib/bookSearch.test.ts lib/inlineShortcodes.test.ts lib/directiveBlocks.test.ts"
   },
   "dependencies": {
     "hast-util-to-jsx-runtime": "^2.3.6",