feat: normalize release-cardinal fields out of track into a Release entity (Phase 8 §8.0)

DeepDrftModels/Entities/TrackEntity.cs

@@ -1,4 +1,3 @@
-using DeepDrftModels.Enums;
 using Models.Entities;
 
 namespace DeepDrftModels.Entities;
@@ -6,17 +5,16 @@ namespace DeepDrftModels.Entities;
 // Inherits Id, CreatedAt, UpdatedAt, IsDeleted from BaseEntity (Cerebellum.BlazorBlocks.Models).
 // BaseEntity ships the audit columns but does not declare IEntity itself, so subclasses
 // declare it explicitly to satisfy the generic constraints on Repository<>/Manager<>/etc.
+//
+// Track-cardinal data only (Phase 8 §8.0). Release-cardinal fields (Artist, Album→Title, Genre,
+// ReleaseDate, ImagePath, ReleaseType, CreatedByUserId) live on ReleaseEntity, reached via the
+// nullable Release navigation; ReleaseId is null for singles and loose tracks.
 public class TrackEntity : BaseEntity, IEntity
 {
     public required string EntryKey { get; set; }
     public required string TrackName { get; set; }
-    public required string Artist { get; set; }
-    public string? Album { get; set; }
-    public string? Genre { get; set; }
-    public DateOnly? ReleaseDate { get; set; }
-    public string? ImagePath { get; set; }
-    public long? CreatedByUserId { get; set; }
     public string? OriginalFileName { get; set; }
-    public ReleaseType ReleaseType { get; set; } = ReleaseType.Single;
     public int TrackNumber { get; set; } = 1;
+    public long? ReleaseId { get; set; }
+    public ReleaseEntity? Release { get; set; }
 }