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  tracks are created unpublished.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- An unpublished track is only visible to its owner.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  unpublished totals.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/Albums/UpdateAlbum.cs

@@ -5,6 +5,7 @@ using Microsoft.Extensions.Logging;
 using Musify.Application.Albums.Responses;
 using Musify.Application.Contracts;
 using Musify.Application.Shared;
+using Musify.Domain.ValueObjects;
 
 namespace Musify.Application.Albums
 {
@@ -13,7 +14,8 @@ namespace Musify.Application.Albums
         Guid AlbumId,
         string Title,
         string? Description,
-        int? ReleaseYear)
+        int? ReleaseYear,
+        AlbumType? Type = null)
         : ICommand<ErrorOr<AlbumApplicationResponse>>;
 
     public class UpdateAlbumCommandHandler(
@@ -34,6 +36,7 @@ namespace Musify.Application.Albums
             album.NormalizedTitle = TextNormalizer.Normalize(title);
             album.Description = string.IsNullOrWhiteSpace(request.Description) ? null : request.Description.Trim();
             album.ReleaseYear = request.ReleaseYear;
+            album.Type = request.Type ?? album.Type;
 
             await database.SaveChangesAsync(cancellationToken);