fix: 首页默认排序改为最近活动时间线

reply 按发帖与最后评论的较晚时间混排，零回复新帖不再沉底；默认文案改为「最新」。

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

frontend/src/api/types.ts

@@ -224,7 +224,7 @@ export interface FeedSortTab {
 }
 
 export const DEFAULT_FEED_SORT_TABS: FeedSortTab[] = [
-  { id: 'reply', label: '新评论', enabled: true },
+  { id: 'reply', label: '最新', enabled: true },
   { id: 'latest', label: '新帖子', enabled: true },
   { id: 'hot', label: '推荐帖', enabled: true },
 ];

frontend/src/components/FeedSortBar.tsx

@@ -15,7 +15,7 @@ import type { FeedSortTab } from '../api/types';
 export type FeedSort = 'latest' | 'reply' | 'hot';
 
 const SORT_META: Record<FeedSort, { hint: string; icon: typeof Clock }> = {
-  reply: { hint: '最近有人评论', icon: MessageCircle },
+  reply: { hint: '按最近活动（发帖或评论）', icon: MessageCircle },
   latest: { hint: '按发帖时间', icon: Clock },
   hot: { hint: '仅展示推荐帖', icon: BadgeCheck },
 };

frontend/src/components/admin/FeedSortTabList.tsx

@@ -5,7 +5,7 @@ import type { FeedSortId, FeedSortTab } from '../../api/types';
 import { normalizeFeedSortTabs } from '../../utils/feedSortTabs';
 
 const TAB_META: Record<FeedSortId, { hint: string; placeholder: string }> = {
-  reply: { hint: '按最后评论时间', placeholder: '新评论' },
+  reply: { hint: '按最近活动（发帖或评论）', placeholder: '最新' },
   latest: { hint: '按发帖时间', placeholder: '新帖子' },
   hot: { hint: '仅展示推荐帖', placeholder: '推荐帖' },
 };

frontend/src/pages/admin/AdminSettingsPage.tsx

@@ -952,7 +952,7 @@ export default function AdminSettingsPage() {
                 <div className="admin-settings-subsection">
                   <h4 className="admin-settings-subsection-title">首页排序标签</h4>
                   <p className="admin-settings-subsection-desc">
-                    拖拽调整顺序；在「显示名称」框中改首页文案；右侧开关控制启停。第一个启用项为默认排序
+                    拖拽调整顺序；在「显示名称」框中改首页文案；右侧开关控制启停。第一个启用项为默认排序。「最新」按发帖与评论的最近时间混排
                   </p>
                   <FeedSortTabList
                     tabs={normalizeFeedSortTabs(limits.feed_sort_tabs ?? DEFAULT_FEED_SORT_TABS)}

frontend/src/utils/feedSortTabs.ts

@@ -4,7 +4,7 @@ import { DEFAULT_FEED_SORT_TABS } from '../api/types';
 const FEED_SORT_IDS: FeedSortId[] = ['reply', 'latest', 'hot'];
 
 const DEFAULT_LABELS: Record<FeedSortId, string> = {
-  reply: '新评论',
+  reply: '最新',
   latest: '新帖子',
   hot: '推荐帖',
 };