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/scripts/fetch-dy-emoji.mjs

@@ -0,0 +1,129 @@
+/**
+ * 一次性资产脚本：从 github.com/rento666/douyin-emoji 下载表情图片存档，
+ * 拍平拷贝到 frontend/public/emoji/dy/ 并生成 manifest.json。
+ *
+ * 用法：node scripts/fetch-dy-emoji.mjs
+ * 产物（图片 + manifest.json）需提交进 git；重复执行会先清空目标目录。
+ */
+import { execFileSync } from "node:child_process";
+import { createWriteStream, existsSync, mkdirSync, rmSync, statSync } from "node:fs";
+import { readdir, writeFile, cp } from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { Readable } from "node:stream";
+import { pipeline } from "node:stream/promises";
+
+const REPO_ZIPS = [
+  // 国内网络下 GitHub 直连常被限速，优先走镜像加速（实测 gh-proxy.com 可达 MB/s 级）
+  "https://gh-proxy.com/https://github.com/rento666/douyin-emoji/archive/refs/heads/main.zip",
+  "https://codeload.github.com/rento666/douyin-emoji/zip/refs/heads/main",
+  "https://github.com/rento666/douyin-emoji/archive/refs/heads/main.zip",
+];
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+const FRONTEND = path.resolve(HERE, "..");
+const DEST = path.join(FRONTEND, "public", "emoji", "dy");
+
+async function downloadZip(url, file) {
+  const res = await fetch(url, { redirect: "follow", signal: AbortSignal.timeout(120_000) });
+  if (!res.ok || !res.body) throw new Error(`下载失败 HTTP ${res.status}: ${url}`);
+  await pipeline(Readable.fromWeb(res.body), createWriteStream(file));
+}
+
+async function downloadZipWithFallback(file) {
+  let lastErr;
+  for (const url of REPO_ZIPS) {
+    try {
+      console.log(`尝试 ${url}`);
+      await downloadZip(url, file);
+      return;
+    } catch (e) {
+      lastErr = e;
+      console.warn(`下载失败：${e.message}`);
+    }
+  }
+  throw lastErr;
+}
+
+function extractZip(zip, dir) {
+  // Win10+/Linux 自带 bsdtar，可直接解 zip，无需额外依赖
+  execFileSync("tar", ["-xf", zip, "-C", dir], { stdio: "inherit" });
+}
+
+async function collectPng(dir) {
+  const out = [];
+  for (const name of await readdir(dir)) {
+    const p = path.join(dir, name);
+    if (statSync(p).isDirectory()) out.push(...(await collectPng(p)));
+    else if (name.toLowerCase().endsWith(".png")) out.push(p);
+  }
+  return out;
+}
+
+async function main() {
+  if (!existsSync(DEST)) mkdirSync(DEST, { recursive: true });
+  const tmp = await readdir(os.tmpdir()).then(() => os.tmpdir());
+  const work = path.join(tmp, `dy-emoji-${Date.now()}`);
+  mkdirSync(work, { recursive: true });
+  const zip = path.join(work, "repo.zip");
+
+  console.log("下载仓库压缩包…");
+  await downloadZipWithFallback(zip);
+  console.log("解压…");
+  extractZip(zip, work);
+  const repo = path.join(work, "douyin-emoji-main", "dy_emojis");
+
+  const tosDir = path.join(repo, "tos_emoji");
+  const fusDir = path.join(repo, "fus_emoji");
+  if (!existsSync(tosDir) || !existsSync(fusDir)) {
+    throw new Error(`仓库结构不符合预期：${repo}`);
+  }
+
+  const tosFiles = await collectPng(tosDir);
+  const fusFiles = await collectPng(fusDir);
+  if (tosFiles.length === 0 || fusFiles.length === 0) {
+    throw new Error(`表情文件为空：tos=${tosFiles.length} fus=${fusFiles.length}`);
+  }
+
+  // 拍平拷贝：目标目录清空后写入，文件名唯一性校验
+  rmSync(DEST, { recursive: true, force: true });
+  mkdirSync(DEST, { recursive: true });
+  const seen = new Map();
+  const tos = [];
+  const fus = [];
+  let bytes = 0;
+  for (const [group, files] of [
+    ["tos", tosFiles],
+    ["fus", fusFiles],
+  ]) {
+    for (const f of files) {
+      const key = path.basename(f, ".png");
+      if (!/^[A-Za-z0-9_-]+$/.test(key)) {
+        throw new Error(`文件名含非法字符（会破坏短代码）：${key}`);
+      }
+      if (seen.has(key)) throw new Error(`文件名冲突：${key}（${f} 与 ${seen.get(key)}）`);
+      seen.set(key, f);
+      await cp(f, path.join(DEST, `${key}.png`));
+      bytes += statSync(f).size;
+      (group === "tos" ? tos : fus).push(key);
+    }
+  }
+  tos.sort();
+  fus.sort();
+
+  const manifest = { tos, fus };
+  await writeFile(path.join(DEST, "manifest.json"), JSON.stringify(manifest), "utf8");
+
+  console.log(
+    `完成：tos=${tos.length} 张，fus=${fus.length} 张，共 ${(bytes / 1024 / 1024).toFixed(1)}MB → ${DEST}`
+  );
+  console.log(`manifest.json：${path.join(DEST, "manifest.json")}`);
+
+  // 清理临时目录
+  rmSync(work, { recursive: true, force: true });
+}
+
+main().catch((e) => {
+  console.error(e);
+  process.exit(1);
+});