Add XML documentation for Name property validation behavior

Co-authored-by: yeelam-gordon <73506701+yeelam-gordon@users.noreply.github.com>

src/settings-ui/Settings.UI.Library/ImageSize.cs

@@ -65,6 +65,10 @@ public partial class ImageSize : INotifyPropertyChanged, IHasId
         get => !(Unit == ResizeUnit.Percent && Fit != ResizeFit.Stretch);
     }
 
+    /// <summary>
+    /// Gets or sets the name of the image size.
+    /// Invalid values (null, empty, or whitespace) are silently ignored to maintain the existing name.
+    /// </summary>
     [JsonPropertyName("name")]
     public string Name
     {