feat: 优化图片加载和展示功能

- 新增 SmartImage 组件优化图片加载体验
- 新增 ImageGrid 组件支持多图布局展示
- 新增 imageHelper 工具函数
- 优化 PostCard 帖子卡片图片展示
- 优化消息页面 SegmentRenderer
- 优化日程页面 ScheduleScreen
- 优化上传服务 uploadService

src/components/business/PostCard.tsx

@@ -20,6 +20,7 @@ import Avatar from '../common/Avatar';
 import { ImageGrid, ImageGridItem, SmartImage } from '../common';
 import VotePreview from './VotePreview';
 import { useResponsive, useResponsiveValue } from '../../hooks/useResponsive';
+import { getPreviewImageUrl, ImageDisplayMode } from '../../utils/imageHelper';
 
 interface PostCardProps {
   post: Post;
@@ -206,6 +207,8 @@ const PostCard: React.FC<PostCardProps> = ({
       id: img.id,
       url: img.url,
       thumbnail_url: img.thumbnail_url,
+      preview_url: img.preview_url,
+      preview_url_large: img.preview_url_large,
       width: img.width,
       height: img.height,
     }));
@@ -224,6 +227,8 @@ const PostCard: React.FC<PostCardProps> = ({
           borderRadius={imageBorderRadius}
           showMoreOverlay={true}
           onImagePress={onImagePress}
+          displayMode={variant === 'grid' ? 'grid' : 'list'}
+          usePreview={true}
         />
       </View>
     );
@@ -335,6 +340,11 @@ const PostCard: React.FC<PostCardProps> = ({
     const aspectRatios = [0.7, 0.75, 0.8, 0.85, 0.9, 1, 1.1, 1.2];
     const aspectRatio = aspectRatios[hash % aspectRatios.length];
 
+    // 获取封面图预览 URL
+    const coverUrl = hasImage
+      ? getPreviewImageUrl(coverImage, 'grid')
+      : '';
+
     // 获取正文预览（无图时显示）
     const getContentPreview = (content: string | undefined | null): string => {
       if (!content) return '';
@@ -369,9 +379,10 @@ const PostCard: React.FC<PostCardProps> = ({
             onPress={() => onImagePress?.(post.images || [], 0)}
           >
             <SmartImage
-              source={{ uri: coverImage.thumbnail_url || coverImage.url || '' }}
+              source={{ uri: coverUrl }}
               style={[styles.gridCoverImage, { aspectRatio }]}
               resizeMode="cover"
+              usePreview={true}
             />
           </TouchableOpacity>
         )}