Refine WinUI shell and improve render diagnostics

AmiReel.WinUI/MainWindow.xaml.cs

@@ -1,4 +1,6 @@
 using Microsoft.UI.Xaml;
+using System;
+using System.IO;
 
 // To learn more about WinUI, the WinUI project structure,
 // and more about our project templates, see: http://aka.ms/winui-project-info.
@@ -19,7 +21,9 @@ public sealed partial class MainWindow : Window
         ExtendsContentIntoTitleBar = true;
         SetTitleBar(AppTitleBar);
 
-        AppWindow.SetIcon("Assets/AppIcon.ico");
+        string? executablePath = Environment.ProcessPath;
+        if (!string.IsNullOrWhiteSpace(executablePath) && File.Exists(executablePath))
+            AppWindow.SetIcon(executablePath);
 
         // Navigate the root frame to the main page on startup.
         RootFrame.Navigate(typeof(MainPage));