make icon size a variable

Program.cs

@@ -505,14 +505,16 @@ public static class Util {
   }
 
   public static OpenTK.Windowing.Common.Input.Image[] RenderAppIcon() {
-    Font font = SystemFonts.CreateFont("MS PMincho", 64, FontStyle.Bold);
+    int size = 64;
+    Font font = SystemFonts.CreateFont("MS PMincho", size, FontStyle.Bold);
     TextOptions options = new(font);
-    Image<Rgba32> image = MakeImage(64, 64);
+    Image<Rgba32> image = MakeImage(size, size);
     IBrush brush = Brushes.Solid(Color.Black);
     image.Mutate(x => x.DrawText(options, "撮", brush));
-    byte[] pixelBytes = new byte[64 * 64 * 4];
+    byte[] pixelBytes = new byte[size * size * 4];
     image.CopyPixelDataTo(pixelBytes);
-    OpenTK.Windowing.Common.Input.Image opentkImage = new(64, 64, pixelBytes);
+    image.Dispose();
+    OpenTK.Windowing.Common.Input.Image opentkImage = new(size, size, pixelBytes);
     return new OpenTK.Windowing.Common.Input.Image[]{ opentkImage };
   }