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/common/ImageGrid.tsx

@@ -2,6 +2,7 @@
  * ImageGrid 图片网格组件
  * 支持 1-9 张图片的智能布局
  * 根据图片数量自动选择最佳展示方式
+ * 支持预览图优化
  */
 
 import React, { useMemo, useCallback, useState, useEffect } from 'react';
@@ -16,6 +17,7 @@ import {
 } from 'react-native';
 import { SmartImage, ImageSource } from './SmartImage';
 import { colors, spacing, borderRadius } from '../../theme';
+import { getPreviewImageUrl, ImageDisplayMode } from '../../utils/imageHelper';
 
 const { width: SCREEN_WIDTH } = Dimensions.get('window');
 
@@ -69,6 +71,10 @@ export interface ImageGridProps {
   onImagePress?: (images: ImageGridItem[], index: number) => void;
   /** 测试ID */
   testID?: string;
+  /** 显示模式 */
+  displayMode?: ImageDisplayMode;
+  /** 是否使用预览图 */
+  usePreview?: boolean;
 }
 
 /**
@@ -201,6 +207,7 @@ const SingleImageItem: React.FC<SingleImageItemProps> = ({
 /**
  * 图片网格组件
  * 智能布局：根据图片数量自动选择最佳展示方式
+ * 支持预览图优化
  */
 export const ImageGrid: React.FC<ImageGridProps> = ({
   images,
@@ -214,6 +221,8 @@ export const ImageGrid: React.FC<ImageGridProps> = ({
   gridColumns = 3,
   onImagePress,
   testID,
+  displayMode = 'list',
+  usePreview = true,
 }) => {
   // 通过 onLayout 拿到容器实际宽度
   const [containerWidth, setContainerWidth] = useState(0);
@@ -256,6 +265,12 @@ export const ImageGrid: React.FC<ImageGridProps> = ({
   const renderSingleImage = () => {
     const image = displayImages[0];
     if (!image) return null;
+    
+    // 获取预览图 URL
+    const previewUrl = usePreview && displayMode
+      ? getPreviewImageUrl(image as any, displayMode)
+      : (image.uri || image.url || '');
+    
     return (
       <SingleImageItem
         image={image}
@@ -271,27 +286,33 @@ export const ImageGrid: React.FC<ImageGridProps> = ({
   const renderHorizontal = () => {
     return (
       <View style={[styles.horizontalContainer, { gap }]}>
-        {displayImages.map((image, index) => (
-          <Pressable
-            key={image.id || index}
-            onPress={() => handleImagePress(index)}
-            style={[
-              styles.horizontalItem,
-              {
-                flex: 1,
-                aspectRatio: 1,
-                borderRadius: borderRadiusValue,
-              },
-            ]}
-          >
-            <SmartImage
-              source={{ uri: image.uri || image.url, width: image.width, height: image.height }}
-              style={styles.fullSize}
-              resizeMode="cover"
-              borderRadius={borderRadiusValue}
-            />
-          </Pressable>
-        ))}
+        {displayImages.map((image, index) => {
+          const previewUrl = usePreview && displayMode
+            ? getPreviewImageUrl(image as any, displayMode)
+            : (image.uri || image.url || '');
+          
+          return (
+            <Pressable
+              key={image.id || index}
+              onPress={() => handleImagePress(index)}
+              style={[
+                styles.horizontalItem,
+                {
+                  flex: 1,
+                  aspectRatio: 1,
+                  borderRadius: borderRadiusValue,
+                },
+              ]}
+            >
+              <SmartImage
+                source={{ uri: previewUrl }}
+                style={styles.fullSize}
+                resizeMode="cover"
+                borderRadius={borderRadiusValue}
+              />
+            </Pressable>
+          );
+        })}
       </View>
     );
   };
@@ -303,6 +324,10 @@ export const ImageGrid: React.FC<ImageGridProps> = ({
         {displayImages.map((image, index) => {
           const isLastVisible = index === displayImages.length - 1;
           const showOverlay = isLastVisible && remainingCount > 0 && showMoreOverlay;
+          
+          const previewUrl = usePreview && displayMode
+            ? getPreviewImageUrl(image as any, displayMode)
+            : (image.uri || image.url || '');
 
           return (
             <Pressable
@@ -317,7 +342,7 @@ export const ImageGrid: React.FC<ImageGridProps> = ({
               ]}
             >
               <SmartImage
-                source={{ uri: image.uri || image.url, width: image.width, height: image.height }}
+                source={{ uri: previewUrl }}
                 style={styles.fullSize}
                 resizeMode="cover"
                 borderRadius={borderRadiusValue}
@@ -361,6 +386,10 @@ export const ImageGrid: React.FC<ImageGridProps> = ({
               ? image.width / image.height
               : 1;
             const height = itemWidth / aspectRatio;
+            
+            const previewUrl = usePreview && displayMode
+              ? getPreviewImageUrl(image as any, displayMode)
+              : (image.uri || image.url || '');
 
             return (
               <Pressable
@@ -376,7 +405,7 @@ export const ImageGrid: React.FC<ImageGridProps> = ({
                 ]}
               >
                 <SmartImage
-                  source={{ uri: image.uri || image.url, width: image.width, height: image.height }}
+                  source={{ uri: previewUrl }}
                   style={styles.fullSize}
                   resizeMode="cover"
                   borderRadius={borderRadiusValue}