Added default layout name for dxfsettings

inabox.dxf/DxfUtils.cs

@@ -24,7 +24,7 @@ public class DxfImportSettings
     {
         ImageSize = imageSize ?? new(2048, 2048);
         SupportFolders = supportFolders;
-        LayoutName = layoutName;
+        LayoutName = layoutName ?? "Model";
     }
 }