Fix variable name in Breadcrumb's child added method

Correct the variable name in the `AnimatedStack_ChildAdded` method
from `firstBreadcrumb` to `lastBreadcrumb` to accurately reflect
the logic of waiting for the last breadcrumb to be fully rendered
before proceeding.

Author: IeuanWalker

Scr/Breadcrumb.xaml.cs

@@ -274,7 +274,7 @@ async void AnimatedStack_ChildAdded(object? sender, ElementEventArgs e)
 	{
 		await Task.Run(async () =>
 		{
-			while(BreadCrumbContainer.Children.LastOrDefault() is not View firstBreadcrumb || firstBreadcrumb.Width <= 0)
+			while(BreadCrumbContainer.Children.LastOrDefault() is not View lastBreadcrumb || lastBreadcrumb.Width <= 0)
 			{
 				await Task.Delay(100);
 			}