Fix MediaSources null array fields and add logging for artist albums

- Added MediaStreams, MediaAttachments, Formats as empty arrays instead of null
- Added RunTimeTicks field to MediaSources
- Added detailed logging to GetExternalChildItems to debug artist album issues
- This should fix 'type Null is not a subtype of type List<dynamic>' error

allstarr/Controllers/JellyfinController.cs

@@ -598,9 +598,13 @@ public class JellyfinController : ControllerBase
     {
         var itemTypes = ParseItemTypes(includeItemTypes);
 
+        _logger.LogInformation("GetExternalChildItems: provider={Provider}, externalId={ExternalId}, itemTypes={ItemTypes}", 
+            provider, externalId, string.Join(",", itemTypes ?? Array.Empty<string>()));
+
         // Check if asking for audio (album tracks)
         if (itemTypes?.Contains("Audio") == true)
         {
+            _logger.LogDebug("Fetching album tracks for {Provider}/{ExternalId}", provider, externalId);
             var album = await _metadataService.GetAlbumAsync(provider, externalId);
             if (album == null)
             {
@@ -611,9 +615,12 @@ public class JellyfinController : ControllerBase
         }
 
         // Otherwise assume it's artist albums
+        _logger.LogDebug("Fetching artist albums for {Provider}/{ExternalId}", provider, externalId);
         var albums = await _metadataService.GetArtistAlbumsAsync(provider, externalId);
         var artist = await _metadataService.GetArtistAsync(provider, externalId);
 
+        _logger.LogInformation("Found {Count} albums for artist {ArtistName}", albums.Count, artist?.Name ?? "unknown");
+
         // Fill artist info
         if (artist != null)
         {

allstarr/Services/Jellyfin/JellyfinResponseBuilder.cs

@@ -326,7 +326,11 @@ public class JellyfinResponseBuilder
                     ["RequiresClosing"] = false,
                     ["RequiresLooping"] = false,
                     ["SupportsProbing"] = true,
-                    ["ReadAtNativeFramerate"] = false
+                    ["ReadAtNativeFramerate"] = false,
+                    ["MediaStreams"] = new List<object>(),  // Empty array instead of null
+                    ["MediaAttachments"] = new List<object>(),  // Empty array instead of null
+                    ["Formats"] = new List<object>(),  // Empty array instead of null
+                    ["RunTimeTicks"] = (song.Duration ?? 180) * 10000000L  // Duration in ticks (100ns units)
                 }
             };
         }