Add proper cancellation and error handling to background cover art caching

- Add CancellationTokenSource field to manage background operations
- Wrap fire-and-forget Task.Run with try-catch for error handling
- Pass cancellation token through EnsureAllCoverArtCachedForSongsAsync
- Reduce parallelism on Android (4 vs 8 on Windows) to lower memory pressure
- Add cancellation checks in the processing loop
- Dispose cancellation token properly in Dispose method

This prevents Android crashes caused by unhandled exceptions and excessive memory usage during background cover image cache scanning.

Co-authored-by: YBTopaz8 <41630728+YBTopaz8@users.noreply.github.com>

Author: Copilot

Dimmer/Dimmer/ViewModel/BaseViewModel.cs

@@ -678,16 +678,28 @@ await lastFMRealm.WriteAsync(() =>
         var duration = endTime - startTime;
         Debug.WriteLine(
             $"{DateTime.Now}: Finished InitializeAllVMCoreComponentsAsync in {duration.TotalSeconds} seconds.");
+        
+        // Initialize background caching with proper error handling and cancellation support
+        _backgroundCachingCts = new CancellationTokenSource();
         _ = Task.Run(async () =>
         {
-            await OnAppOpening();
-            await HeavierBackGroundLoadings(FolderPaths);
+            try
+            {
+                await OnAppOpening();
+                await HeavierBackGroundLoadings(FolderPaths);
 
-            await Task.Delay(3000);
-            await EnsureAllCoverArtCachedForSongsAsync();
-            CancellationTokenSource cts = new();
-            //await LoadAllSongsLyricsFromOnlineAsync(cts);
-        });
+                await Task.Delay(3000, _backgroundCachingCts.Token);
+                await EnsureAllCoverArtCachedForSongsAsync(_backgroundCachingCts.Token);
+            }
+            catch (OperationCanceledException)
+            {
+                _logger.LogInformation("Background cover art caching was cancelled.");
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Error during background initialization and cover art caching.");
+            }
+        }, _backgroundCachingCts.Token);
 
         IsInitialized = true;
         return;
@@ -1389,6 +1401,9 @@ public async Task PlayPlaylist(PlaylistModelView? playlist)
     public IDimmerAudioService AudioService => _audioService;
     private ILibraryScannerService libScannerService;
 
+    // Cancellation token for background cover art caching to prevent memory issues on Android
+    private CancellationTokenSource? _backgroundCachingCts;
+
     public CompositeDisposable SubsManager => _subsManager;
     private readonly CompositeDisposable _subsManager = new CompositeDisposable();
 
@@ -2334,7 +2349,7 @@ public async Task LoadAndCacheCoverArtAsync(SongModelView song)
     [ObservableProperty]
     public partial Progress<(int current, int total, SongModelView song)> ProgressCoverArtLoad { get; set; }
     [RelayCommand]
-    public async Task EnsureAllCoverArtCachedForSongsAsync()
+    public async Task EnsureAllCoverArtCachedForSongsAsync(CancellationToken cancellationToken = default)
     {
         IsAppLoadingCovers = true;
         // 1. Get the TOTAL count safely using a short-lived Realm instance
@@ -2354,9 +2369,13 @@ public async Task EnsureAllCoverArtCachedForSongsAsync()
 
         int processedCount = 0;
 
+        // Use lower parallelism on Android to reduce memory pressure
+        var maxParallelism = DeviceInfo.Platform == DevicePlatform.Android ? 4 : 8;
+        
         var parallelOptions = new ParallelOptions
         {
-            MaxDegreeOfParallelism = 8
+            MaxDegreeOfParallelism = maxParallelism,
+            CancellationToken = cancellationToken
         };
         var batches = songsToProcessIds.Chunk(20);
 
@@ -2377,6 +2396,9 @@ await Parallel.ForEachAsync(batches, parallelOptions, async (batchOfIds, ct) =>
             }
             foreach (var songView in songsInBatch)
             {
+                // Check cancellation before processing each song
+                ct.ThrowIfCancellationRequested();
+                
                 bool needsProcessing = string.IsNullOrEmpty(songView.CoverImagePath)
                                        || !TaggingUtils.FileExists(songView.CoverImagePath);
 
@@ -5135,6 +5157,11 @@ protected virtual void Dispose(bool disposing)
 
         if (disposing)
         {
+            // Cancel background caching operations
+            _backgroundCachingCts?.Cancel();
+            _backgroundCachingCts?.Dispose();
+            _backgroundCachingCts = null;
+            
             _realmSubscription?.Dispose();
             _playEventSource.Dispose();
             realm?.Dispose();