feat(frontend): Markdown 支持 GFM、代码高亮与图片灯箱

统一 SSR/客户端渲染路径，评论与预览共用增强组件。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/components/MarkdownBodyClient.tsx

@@ -0,0 +1,32 @@
+"use client";
+
+import ReactMarkdown, { type Components } from "react-markdown";
+import remarkGfm from "remark-gfm";
+import { mergeMarkdownComponents } from "@/components/markdown/mergeComponents";
+
+type MarkdownBodyClientProps = {
+  content: string;
+  className?: string;
+  components?: Components;
+};
+
+/**
+ * 客户端 Markdown（发帖预览 / 评论）：GFM + 图箱 / 代码折叠复制。
+ * 语法高亮在 MdCodeBlock 内按需用 Shiki 补齐。
+ */
+export default function MarkdownBodyClient({
+  content,
+  className = "prose-content",
+  components,
+}: MarkdownBodyClientProps) {
+  return (
+    <div className={className}>
+      <ReactMarkdown
+        remarkPlugins={[remarkGfm]}
+        components={mergeMarkdownComponents(components)}
+      >
+        {content || ""}
+      </ReactMarkdown>
+    </div>
+  );
+}