feat(release): add plain-text Description field plumbed CMS->DTO->release (11.G)

New nullable Description column (max 4000) on ReleaseEntity, rides the Genre write channel through upload + edit; multiline CMS input. Migration authored, not applied.

DeepDrftModels/DTOs/ReleaseDto.cs

@@ -12,6 +12,7 @@ public class ReleaseDto : BaseModel
     public string Title { get; set; } = string.Empty;
     public string Artist { get; set; } = string.Empty;
     public string? Genre { get; set; }
+    public string? Description { get; set; }
     public DateOnly? ReleaseDate { get; set; }
     public string? ImagePath { get; set; }
     public ReleaseMedium Medium { get; set; } = ReleaseMedium.Cut;

DeepDrftModels/Entities/ReleaseEntity.cs

@@ -15,6 +15,10 @@ public class ReleaseEntity : BaseEntity, IEntity
     public required string Title { get; set; }
     public required string Artist { get; set; }
     public string? Genre { get; set; }
+    // Free-text prose blurb describing the release. Uniform across media (Cut/Session/Mix), so it
+    // lives on the base table alongside Genre rather than in a per-medium satellite. Plain text,
+    // max 4000 (configured in ReleaseConfiguration); nullable so existing rows migrate as NULL.
+    public string? Description { get; set; }
     public DateOnly? ReleaseDate { get; set; }
     public string? ImagePath { get; set; }
     public ReleaseType ReleaseType { get; set; } = ReleaseType.Single;