chore: update styles, add splash config, and improve search functionality

- Replace deprecated StyleSheet.absoluteFillObject with StyleSheet.absoluteFill (React Native 0.76+)
- Add splash screen configuration in app.json
- Fix duplicate UIBackgroundModes and add audio mode for iOS
- Disable Android ripple effect on tab bar buttons
- Improve SmartImage loading state to prevent unnecessary re-renders
- Refactor ImageGrid to use mainUri with separate previewUrl for better preview handling
- Add market search support with trade items tab in SearchScreen
- Pass homeTab prop to SearchScreen for context-aware search behavior
- Simplify fetchUnreadCount return type to void in MessageSyncService
- Fix StatusBar import from expo to react-native in ChatScreen

src/components/common/SmartImage.tsx

@@ -30,7 +30,7 @@ function createSmartImageStyles(colors: AppColors) {
       flex: 1,
     },
     overlay: {
-      ...StyleSheet.absoluteFillObject,
+      ...StyleSheet.absoluteFill,
       justifyContent: 'center',
       alignItems: 'center',
       backgroundColor: colors.background.disabled,
@@ -186,7 +186,8 @@ export const SmartImage: React.FC<SmartImageProps> = ({
     if (isUpgradingFromPreview.current) {
       return;
     }
-    setLoadState('loading');
+    // 已成功加载的图片不再回到loading状态（列表回收/re-render时onLoadStart可能重新触发）
+    setLoadState(prev => (prev === 'success' ? prev : 'loading'));
   }, []);
 
   // 处理加载完成