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

app.json

@@ -7,14 +7,17 @@
     "icon": "./assets/icon.png",
     "userInterfaceStyle": "automatic",
     "scheme": "withyou",
+    "splash": {
+      "image": "./assets/splash-icon.png",
+      "resizeMode": "contain",
+      "backgroundColor": "#ffffff"
+    },
     "ios": {
       "supportsTablet": true,
       "infoPlist": {
         "NSMicrophoneUsageDescription": "允许威友访问您的麦克风以进行语音通话",
         "NSCameraUsageDescription": "允许威友访问您的相机以进行视频通话",
         "UIBackgroundModes": [
-          "fetch",
-          "remote-notification",
           "fetch",
           "remote-notification",
           "audio"