DynamicColorTool: improve layout and update demo defaults

- Removes the ScrollViewer from the main layout of DynamicColorTool.
- Sets the navigation drawer to be closed by default in the demo application.
- Modernizes collection initialization in DynamicColorToolViewModel using collection expressions.
- Adjusts the Z-order and hit testing for the copy color button in the color tiles to improve interaction.

Author: Keboo

src/MaterialDesign3.Demo.Wpf/Domain/DynamicColorToolViewModel.cs

@@ -369,13 +369,13 @@ public IReadOnlyList<DynamicColorGridTile> CustomTonalPaletteTiles
     {
         get;
         private set => SetProperty(ref field, value);
-    } = Array.Empty<DynamicColorGridTile>();
+    } = [];
 
     public IReadOnlyList<DynamicColorGridTile> CustomSemanticColorTiles
     {
         get;
         private set => SetProperty(ref field, value);
-    } = Array.Empty<DynamicColorGridTile>();
+    } = [];
 
     public Brush PrimaryBrush => CreateBrush(PrimaryColor);