Clean up domain entities: shared picture value object, lifecycle and ownership interfaces, explicit tables

backend/Core/Musify.Domain/Entities/UserHasTrack.cs

@@ -1,23 +1,19 @@
-using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
 
 namespace Musify.Domain.Entities;
 
-#pragma warning disable CS8618
 [Table("UserHasTrack")]
 public class UserHasTrack
 {
     public Guid Id { get; set; } = Guid.NewGuid();
 
-    [Required]
     public required long UserId { get; set; }
 
-    [Required]
     public required Guid TrackId { get; set; }
 
     [ForeignKey(nameof(UserId))]
-    public User User { get; set; }
+    public User User { get; set; } = null!;
 
     [ForeignKey(nameof(TrackId))]
-    public Track Track { get; set; }
+    public Track Track { get; set; } = null!;
 }