refactor(PostCard, PostCardGrid, HomeScreen): enhance PostCard component and remove PostCardGrid

- Introduced a new PostCardRelativeTime component for dynamic time display, improving user experience with real-time updates.
- Refactored PostCard to utilize memoization for performance optimization and prevent unnecessary re-renders.
- Removed the PostCardGrid component to streamline the codebase, consolidating functionality within the PostCard component.
- Updated HomeScreen to leverage the new PostCard features, ensuring consistent post rendering and interaction handling.

src/components/business/PostCard/PostCard.tsx

@@ -12,8 +12,8 @@
  * />
  */
 
-import React, { useMemo, useState } from 'react';
-import { View, TouchableOpacity, StyleSheet, Alert } from 'react-native';
+import React, { useMemo, useState, memo, useEffect } from 'react';
+import { View, TouchableOpacity, StyleSheet, Alert, TextStyle } from 'react-native';
 import { MaterialCommunityIcons } from '@expo/vector-icons';
 import { PostCardProps, PostCardAction } from './types';
 import { ImageGridItem, SmartImage } from '../../common';
@@ -23,12 +23,95 @@ import { colors, spacing, borderRadius, fontSizes } from '../../../theme';
 import { getPreviewImageUrl } from '../../../utils/imageHelper';
 import PostImages from './components/PostImages';
 import { useResponsive } from '../../../hooks/useResponsive';
+import { formatPostCreatedAtString } from '../../../core/entities/Post';
+
+/** 列表相对时间：独立定时刷新，避免外层 PostCard.memo 挡住「分钟前」更新 */
+const PostCardRelativeTime: React.FC<{ createdAt?: string | null; style?: TextStyle | TextStyle[] }> = ({
+  createdAt,
+  style: timeStyle,
+}) => {
+  const [label, setLabel] = useState(() => formatPostCreatedAtString(createdAt));
+
+  useEffect(() => {
+    setLabel(formatPostCreatedAtString(createdAt));
+    const tick = () => setLabel(formatPostCreatedAtString(createdAt));
+    const id = setInterval(tick, 60_000);
+    return () => clearInterval(id);
+  }, [createdAt]);
+
+  return (
+    <Text style={timeStyle} numberOfLines={1}>
+      {label}
+    </Text>
+  );
+};
+
+function imagesSignature(
+  images: PostCardProps['post']['images'] | undefined
+): string {
+  if (!images?.length) return '';
+  return images.map((i) => i.id).join('\u001f');
+}
+
+function authorSignature(author: PostCardProps['post']['author']): string {
+  if (!author) return '';
+  return [author.id, author.nickname ?? '', author.avatar ?? ''].join('\u001f');
+}
+
+function topCommentSignature(tc: PostCardProps['post']['top_comment']): string {
+  if (!tc) return '';
+  return [tc.id, tc.content ?? '', tc.author?.id ?? ''].join('\u001f');
+}
+
+function featuresComparable(f: PostCardProps['features']): string {
+  if (f == null) return '';
+  if (typeof f === 'string') return f;
+  return JSON.stringify(f);
+}
+
+/**
+ * 自定义比较：忽略 onAction 引用（父组件应用 postId + ref 解析最新 post，避免 Tab 切换时全列表因回调重建而重绘）。
+ * index 未参与 UI，不比较以免列表重排时多余更新。
+ */
+function arePostCardPropsEqual(prev: PostCardProps, next: PostCardProps): boolean {
+  if (prev.variant !== next.variant) return false;
+  if (prev.isPostAuthor !== next.isPostAuthor) return false;
+  if (prev.isAuthor !== next.isAuthor) return false;
+  if (prev.style !== next.style) return false;
+  if (featuresComparable(prev.features) !== featuresComparable(next.features)) return false;
+
+  const a = prev.post;
+  const b = next.post;
+  if (a === b) return true;
+
+  if (a.id !== b.id) return false;
+  if (a.title !== b.title) return false;
+  if (a.content !== b.content) return false;
+  if ((a.likes_count ?? 0) !== (b.likes_count ?? 0)) return false;
+  if ((a.comments_count ?? 0) !== (b.comments_count ?? 0)) return false;
+  if ((a.favorites_count ?? 0) !== (b.favorites_count ?? 0)) return false;
+  if ((a.shares_count ?? 0) !== (b.shares_count ?? 0)) return false;
+  if ((a.views_count ?? 0) !== (b.views_count ?? 0)) return false;
+  if (!!a.is_pinned !== !!b.is_pinned) return false;
+  if (!!a.is_locked !== !!b.is_locked) return false;
+  if (!!a.is_vote !== !!b.is_vote) return false;
+  if (a.created_at !== b.created_at) return false;
+  if (a.updated_at !== b.updated_at) return false;
+  if (a.content_edited_at !== b.content_edited_at) return false;
+  if (!!a.is_liked !== !!b.is_liked) return false;
+  if (!!a.is_favorited !== !!b.is_favorited) return false;
+  if (authorSignature(a.author) !== authorSignature(b.author)) return false;
+  if (imagesSignature(a.images) !== imagesSignature(b.images)) return false;
+  if (topCommentSignature(a.top_comment) !== topCommentSignature(b.top_comment)) return false;
+
+  return true;
+}
 
 /**
  * PostCard 主组件
  * 仅支持新 API
  */
-const PostCard: React.FC<PostCardProps> = (normalizedProps) => {
+const PostCardInner: React.FC<PostCardProps> = (normalizedProps) => {
   const {
     post,
     onAction,
@@ -247,9 +330,7 @@ const PostCard: React.FC<PostCardProps> = (normalizedProps) => {
             <Text style={styles.authorName} numberOfLines={1}>{author?.nickname || '匿名用户'}</Text>
             {!showGrid && (
               <View style={styles.metaRow}>
-                <Text style={styles.timeText} numberOfLines={1}>
-                  {post.created_at ? new Date(post.created_at).toLocaleDateString() : ''}
-                </Text>
+                <PostCardRelativeTime createdAt={post.created_at} style={styles.timeText} />
                 {post.is_pinned && (
                   <View style={styles.pinnedTag}>
                     <MaterialCommunityIcons name="pin" size={10} color={colors.warning.main} />
@@ -334,6 +415,10 @@ const PostCard: React.FC<PostCardProps> = (normalizedProps) => {
   );
 };
 
+PostCardInner.displayName = 'PostCard';
+
+const PostCard = memo(PostCardInner, arePostCardPropsEqual);
+
 const styles = StyleSheet.create({
   card: {
     backgroundColor: colors.background.paper,