feat: 论坛 emoji 表情支持

- 新增 dyEmoji 表情库与解析测试、EmojiPicker 选择器与 EmojiImg 组件
- Markdown 编辑器/渲染支持表情图片，新增 public/emoji 资源与生成脚本
- 聊天室与首页适配

frontend/components/MarkdownBodyClient.tsx

@@ -4,6 +4,7 @@ import ReactMarkdown, { type Components } from "react-markdown";
 import remarkGfm from "remark-gfm";
 import { mergeMarkdownComponents } from "@/components/markdown/mergeComponents";
 import { splitContentSegments } from "@/lib/directiveBlocks";
+import { expandDyEmojiShortcodes } from "@/lib/dyEmoji";
 import type { HideKind } from "@/lib/hideBlocks";
 import MdHideBlock from "@/components/markdown/MdHideBlock";
 import MdTimeline from "@/components/markdown/MdTimeline";
@@ -28,7 +29,7 @@ export default function MarkdownBodyClient({
   loginHref,
   loggedIn = false,
 }: MarkdownBodyClientProps) {
-  const segs = splitContentSegments(content || "");
+  const segs = splitContentSegments(expandDyEmojiShortcodes(content || ""));
   const mdComponents = mergeMarkdownComponents(components);
   // 时间线/隐藏块正文不套外层 heading 覆盖，避免预览与正文目录 id 错位
   const nestedMd = mergeMarkdownComponents();
@@ -52,7 +53,7 @@ export default function MarkdownBodyClient({
               renderBody={(it) =>
                 it.body.trim() ? (
                   <ReactMarkdown remarkPlugins={[remarkGfm]} components={nestedMd}>
-                    {it.body}
+                    {expandDyEmojiShortcodes(it.body)}
                   </ReactMarkdown>
                 ) : null
               }
@@ -77,7 +78,7 @@ export default function MarkdownBodyClient({
           <MdHideBlock key={`hide-${i}`} kind={kind} points={seg.points}>
             {seg.body.trim() ? (
               <ReactMarkdown remarkPlugins={[remarkGfm]} components={nestedMd}>
-                {seg.body}
+                {expandDyEmojiShortcodes(seg.body)}
               </ReactMarkdown>
             ) : null}
           </MdHideBlock>