修复发帖长文布局与手机下拉刷新，发版后自动重载失效 chunk，并整理站务文案。

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

frontend/src/utils/chunkLoad.ts

@@ -0,0 +1,34 @@
+/** sessionStorage：短时内只自动刷新一次，避免死循环 */
+const RELOAD_AT_KEY = 'j13:chunk-reload-at';
+const RELOAD_COOLDOWN_MS = 15_000;
+
+/** 判断是否为「发版后旧 JS chunk 失效」类错误 */
+export function isChunkLoadError(error: unknown): boolean {
+  const msg = error instanceof Error
+    ? `${error.name} ${error.message}`
+    : String(error ?? '');
+  return /Failed to fetch dynamically imported module/i.test(msg)
+    || /error loading dynamically imported module/i.test(msg)
+    || /Importing a module script failed/i.test(msg)
+    || /Loading chunk [\w-]+ failed/i.test(msg)
+    || /ChunkLoadError/i.test(msg);
+}
+
+/**
+ * 发版后旧页面仍引用已删除的 hashed chunk 时，整页刷新以拉取新 index.html。
+ * @returns 是否已触发刷新（调用方应暂停渲染）
+ */
+export function reloadForStaleChunk(): boolean {
+  try {
+    const prev = Number(sessionStorage.getItem(RELOAD_AT_KEY) || 0);
+    const now = Date.now();
+    if (now - prev < RELOAD_COOLDOWN_MS) {
+      return false;
+    }
+    sessionStorage.setItem(RELOAD_AT_KEY, String(now));
+  } catch {
+    // sessionStorage 不可用时仍尝试刷新一次
+  }
+  window.location.reload();
+  return true;
+}