fix: move gesture-handler and TrackPlayer init to index.js, fix Dimensions usage

mobile/index.js

@@ -1,8 +1,9 @@
+import 'react-native-gesture-handler';
 import { registerRootComponent } from 'expo';
-
+import TrackPlayer from 'react-native-track-player';
+import { PlaybackService } from './src/audio/service';
 import App from './App';
 
-// registerRootComponent calls AppRegistry.registerComponent('main', () => App);
-// It also ensures that whether you load the app in Expo Go or in a native build,
-// the environment is set up appropriately
+TrackPlayer.registerPlaybackService(() => PlaybackService);
+
 registerRootComponent(App);