feat(ui): improve navigation, component props, and chat logic

- update `app.json` with splash screen configuration
- implement tab navigation redirection in `TabsLayout` for apps and profile tabs
- update `HighlightText` prop usage from `style` to `highlightStyle` in `PostCard` and `PostContentRenderer`
- fix chat message segment construction to avoid empty text segments when sending only images
- refine UI styling by removing unnecessary shadows and adjusting `UserScreen` header visibility
- improve `HomeScreen` scroll behavior by disabling animation on FlashList scroll-to-top

src/screens/profile/UserScreen.tsx

@@ -24,7 +24,7 @@ export const UserScreen: React.FC = () => {
       <UserProfileScreen
         mode={isSelfProfile ? 'self' : 'other'}
         userId={isSelfProfile ? undefined : userId}
-        hasHeader={false}
+        hasHeader
       />
     </SafeAreaView>
   );