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  tracks are created unpublished.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- An unpublished track is only visible to its owner.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  unpublished totals.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/Hosts/Musify.Api/DataTransferObjects/Albums/CreateAlbumRequest.cs

@@ -1,8 +1,12 @@
+using Musify.Domain.ValueObjects;
+
 namespace Musify.Api.DataTransferObjects.Albums
 {
     public record CreateAlbumRequest(
         string Title,
         string? Description,
         int? ReleaseYear,
-        Guid PictureIntentId);
+        Guid PictureIntentId,
+        AlbumType Type = AlbumType.Album,
+        IReadOnlyList<Guid>? TrackIds = null);
 }

backend/Hosts/Musify.Api/DataTransferObjects/Albums/UpdateAlbumRequest.cs

@@ -1,7 +1,10 @@
+using Musify.Domain.ValueObjects;
+
 namespace Musify.Api.DataTransferObjects.Albums
 {
     public record UpdateAlbumRequest(
         string Title,
         string? Description,
-        int? ReleaseYear);
+        int? ReleaseYear,
+        AlbumType? Type = null);
 }