初始提交：姜十三论坛 Jiang13 Forum

轻量自用论坛，Go 单二进制 + React SPA 内嵌 + SQLite。

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

frontend/src/utils/comment.ts

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+import type { Comment } from '../api/types';
+
+export interface CommentNode {
+  comment: Comment;
+  children: CommentNode[];
+}
+
+/** 评论显示昵称 */
+export function commentNick(c: Comment): string {
+  if (c.user?.nickname) return c.user.nickname;
+  if (c.guest_nick) return c.guest_nick;
+  return '游客';
+}
+
+/** 评论头像首字 */
+export function commentInitial(c: Comment): string {
+  return commentNick(c)[0] || '?';
+}
+
+/** 是否为游客评论 */
+export function isGuestComment(c: Comment): boolean {
+  return !c.user_id || c.user_id === 0;
+}
+
+/** 构建嵌套评论树（按 reply_to） */
+export function buildCommentTree(comments: Comment[]): CommentNode[] {
+  const map = new Map<number, CommentNode>();
+  const roots: CommentNode[] = [];
+
+  for (const c of comments) {
+    map.set(c.id, { comment: c, children: [] });
+  }
+
+  for (const c of comments) {
+    const node = map.get(c.id)!;
+    if (c.reply_to && map.has(c.reply_to)) {
+      map.get(c.reply_to)!.children.push(node);
+    } else {
+      roots.push(node);
+    }
+  }
+
+  return roots;
+}
+
+/** 评论日期：当年显示 MM月DD日 */
+export function formatCommentDate(iso: string): string {
+  const d = new Date(iso);
+  const now = new Date();
+  const pad = (n: number) => String(n).padStart(2, '0');
+  if (d.getFullYear() === now.getFullYear()) {
+    return `${pad(d.getMonth() + 1)}月${pad(d.getDate())}日`;
+  }
+  return `${d.getFullYear()}年${d.getMonth() + 1}月${d.getDate()}日`;
+}