Create PreloadAttribute.cs

StabilityMatrix.Core/Attributes/PreloadAttribute.cs

@@ -0,0 +1,8 @@
+namespace StabilityMatrix.Core.Attributes;
+
+/// <summary>
+/// Marks that a ViewModel should have its OnLoaded and OnLoadedAsync methods called in the background
+/// during MainWindow initialization, after LibraryDirectory is set.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct)]
+public class PreloadAttribute : Attribute { }