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/components/MarkdownBody.tsx

@@ -7,6 +7,8 @@ import type { HideKind } from "@/lib/hideBlocks";
 import MdHideBlock from "@/components/markdown/MdHideBlock";
 import MdTimeline from "@/components/markdown/MdTimeline";
 import MdEntries from "@/components/markdown/MdEntries";
+import MdDetails from "@/components/markdown/MdDetails";
+import MdVideo from "@/components/markdown/MdVideo";
 
 type MarkdownBodyProps = {
   content: string;
@@ -75,6 +77,21 @@ export default async function MarkdownBody({
       );
       continue;
     }
+    if (seg.type === "details") {
+      const inner = seg.body.trim()
+        ? await renderMarkdownToReact(expandDyEmojiShortcodes(seg.body))
+        : null;
+      nodes.push(
+        <MdDetails key={`details-${i}`} title={seg.title}>
+          {inner}
+        </MdDetails>
+      );
+      continue;
+    }
+    if (seg.type === "video") {
+      nodes.push(<MdVideo key={`video-${i}`} provider={seg.provider} id={seg.id} />);
+      continue;
+    }
     const kind = seg.kind as HideKind;
     if (seg.locked) {
       nodes.push(