Add track publication, album types, optional track pictures and batch upload URLs

Tracks
- Track.IsPublished (migration marks existing tracks as published). New
  tracks are created unpublished.
- PUT /tracks/{id}/published and PUT /tracks/published change the flag;
  publishing requires completed audio processing (the batch endpoint
  reports skipped tracks).
- An unpublished track is only visible to its owner. A WherePublished /
  VisibleTo filter is applied to search, genres, listening history, last
  listened, likes, mixes, album and playlist contents and counts, recently
  listened albums, public user tracks, track details and stream tickets.
- isPublished is part of the track responses, GET /tracks/users/{userId}
  accepts a published filter and status-counts reports published and
  unpublished totals.
- CreateTrackRequest.pictureIntentId is optional: without it the track
  uses the album cover or the preset picture and no picture processing
  runs. CreateTrackResourcesEvent carries nullable picture fields, so
  queues must be drained before deploying.
- POST /tracks/upload-urls accepts an audios list and one optional picture
  shared by all of them, and returns an intent per file. The upload intent
  limits are raised so a batch fits.

Albums
- AlbumType (Album, EP, Single) on create, update and responses.
- CreateAlbumRequest.trackIds creates the album and links the tracks in a
  single save.

backend/Core/Musify.Application/Tracks/GetTrackStatusCounts.cs

@@ -18,18 +18,23 @@ namespace Musify.Application.Tracks
                 .AsNoTracking()
                 .Active()
                 .Where(track => track.OwnerUserId == request.UserId)
-                .GroupBy(track => track.Audio.TranscodeStatus)
-                .Select(group => new { Status = group.Key, Count = group.Count() })
+                .GroupBy(track => new { track.Audio.TranscodeStatus, track.IsPublished })
+                .Select(group => new { group.Key.TranscodeStatus, group.Key.IsPublished, Count = group.Count() })
                 .ToListAsync(cancellationToken);
 
-            int CountOf(ProcessingStatus status) => counts.Where(c => c.Status == status).Sum(c => c.Count);
+            int CountOf(ProcessingStatus status) => counts.Where(c => c.TranscodeStatus == status).Sum(c => c.Count);
+
+            var published = counts.Where(c => c.IsPublished).Sum(c => c.Count);
+            var total = counts.Sum(c => c.Count);
 
             return new TrackStatusCountsResponse(
-                counts.Sum(c => c.Count),
+                total,
                 CountOf(ProcessingStatus.Pending),
                 CountOf(ProcessingStatus.Processing),
                 CountOf(ProcessingStatus.Completed),
-                CountOf(ProcessingStatus.Failed));
+                CountOf(ProcessingStatus.Failed),
+                published,
+                total - published);
         }
     }
 }