fix: avoid syncing beat metadata twice when returning from Now Playing -> Library

app/src/main/java/at/lockstep/player/ui/NowPlayingScreen.kt

@@ -2,6 +2,7 @@ package at.lockstep.player.ui
 
 import android.Manifest
 import android.content.pm.PackageManager
+import androidx.activity.compose.BackHandler
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.foundation.layout.Arrangement
@@ -169,6 +170,7 @@ fun NowPlayingRoute(
     modifier: Modifier = Modifier,
 ) {
     val context = LocalContext.current
+    BackHandler(onBack = onBack)
     val collectRunData by viewModel.collectRunData.collectAsStateWithLifecycle()
     val collector = remember { RunDataCollector(context) }
     val runSessionFolder = remember { RunDataStorage.newRunSessionFolderName() }