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

app.json

@@ -155,7 +155,14 @@
       ],
       "./plugins/withHuaweiPush",
       "expo-callkit-telecom",
-      "expo-splash-screen",
+      [
+        "expo-splash-screen",
+        {
+          "image": "./assets/splash-icon.png",
+          "resizeMode": "contain",
+          "backgroundColor": "#ffffff"
+        }
+      ],
       "expo-status-bar"
     ],
     "extra": {