Extracted some pages to their own assembly and finished the artifact display page code

OpenArchival.DataAccess/ApplicationDbContext.cs

@@ -57,6 +57,11 @@ public class ApplicationDbContext(DbContextOptions<ApplicationDbContext> options
             .HasForeignKey(entry => entry.ArtifactGroupingId)
             .OnDelete(DeleteBehavior.Cascade);
 
+        modelBuilder.Entity<ArtifactEntry>()
+            .HasMany(entry => entry.Files)
+            .WithOne(file => file.ParentArtifactEntry)
+            .OnDelete(DeleteBehavior.Cascade);
+
         modelBuilder.Entity<ArtifactGrouping>()
             .Navigation(g => g.IdentifierFields)
             .UsePropertyAccessMode(PropertyAccessMode.Field);