补齐论坛核心能力：讨论锁定、发帖本地草稿、标签精确筛选，以及私信与通知分流。

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

frontend/src/utils/composeDraft.ts

@@ -0,0 +1,59 @@
+/** 新建帖本地草稿（localStorage） */
+
+const STORAGE_KEY = 'j13-compose-draft-v1';
+
+export type ComposeDraft = {
+  title: string;
+  tags: string;
+  content: string;
+  boardId: string;
+  postType: 'normal' | 'question';
+  savedAt: number;
+};
+
+export function loadComposeDraft(): ComposeDraft | null {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY);
+    if (!raw) return null;
+    const data = JSON.parse(raw) as Partial<ComposeDraft>;
+    if (!data || typeof data !== 'object') return null;
+    return {
+      title: typeof data.title === 'string' ? data.title : '',
+      tags: typeof data.tags === 'string' ? data.tags : '',
+      content: typeof data.content === 'string' ? data.content : '',
+      boardId: typeof data.boardId === 'string' ? data.boardId : '',
+      postType: data.postType === 'question' ? 'question' : 'normal',
+      savedAt: typeof data.savedAt === 'number' ? data.savedAt : Date.now(),
+    };
+  } catch {
+    return null;
+  }
+}
+
+export function saveComposeDraft(draft: Omit<ComposeDraft, 'savedAt'>): void {
+  try {
+    const payload: ComposeDraft = { ...draft, savedAt: Date.now() };
+    localStorage.setItem(STORAGE_KEY, JSON.stringify(payload));
+  } catch {
+    // 配额满或隐私模式：忽略
+  }
+}
+
+export function clearComposeDraft(): void {
+  try {
+    localStorage.removeItem(STORAGE_KEY);
+  } catch {
+    // ignore
+  }
+}
+
+/** 草稿是否有实质内容 */
+export function composeDraftHasContent(d: ComposeDraft | null | undefined): boolean {
+  if (!d) return false;
+  return !!(
+    d.title.trim()
+    || d.tags.trim()
+    || d.content.trim()
+    || (d.content && d.content.replace(/<[^>]*>/g, '').trim())
+  );
+}