Verify Views files against decompiled, extract embedded types

Fixed files:
- SkiaImageButton.cs: Added SVG support with multi-path search
- SkiaNavigationPage.cs: Added LinuxApplication.IsGtkMode check
- SkiaRefreshView.cs: Added ICommand support (Command, CommandParameter)
- SkiaTemplatedView.cs: Added missing using statements

Extracted embedded types to separate files (matching decompiled pattern):
- From SkiaMenuBar.cs: MenuBarItem, MenuItem, SkiaMenuFlyout, MenuItemClickedEventArgs
- From SkiaNavigationPage.cs: NavigationEventArgs
- From SkiaTabbedPage.cs: TabItem
- From SkiaVisualStateManager.cs: SkiaVisualStateGroupList, SkiaVisualStateGroup, SkiaVisualState, SkiaVisualStateSetter
- From SkiaSwipeView.cs: SwipeItem, SwipeStartedEventArgs, SwipeEndedEventArgs
- From SkiaFlyoutPage.cs: FlyoutLayoutBehavior (already separate)
- From SkiaIndicatorView.cs: IndicatorShape (already separate)
- From SkiaBorder.cs: SkiaFrame
- From SkiaCarouselView.cs: PositionChangedEventArgs
- From SkiaCollectionView.cs: SkiaSelectionMode, ItemsLayoutOrientation
- From SkiaContentPresenter.cs: LayoutAlignment

Verified matching decompiled:
- SkiaContextMenu.cs, SkiaFlexLayout.cs, SkiaGraphicsView.cs

Build: 0 errors

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Services/Gtk4InteropService.cs

@@ -5,86 +5,6 @@ using System.Runtime.InteropServices;
 
 namespace Microsoft.Maui.Platform.Linux.Services;
 
-/// <summary>
-/// GTK4 dialog response codes.
-/// </summary>
-public enum GtkResponseType
-{
-    None = -1,
-    Reject = -2,
-    Accept = -3,
-    DeleteEvent = -4,
-    Ok = -5,
-    Cancel = -6,
-    Close = -7,
-    Yes = -8,
-    No = -9,
-    Apply = -10,
-    Help = -11
-}
-
-/// <summary>
-/// GTK4 message dialog types.
-/// </summary>
-public enum GtkMessageType
-{
-    Info = 0,
-    Warning = 1,
-    Question = 2,
-    Error = 3,
-    Other = 4
-}
-
-/// <summary>
-/// GTK4 button layouts for dialogs.
-/// </summary>
-public enum GtkButtonsType
-{
-    None = 0,
-    Ok = 1,
-    Close = 2,
-    Cancel = 3,
-    YesNo = 4,
-    OkCancel = 5
-}
-
-/// <summary>
-/// GTK4 file chooser actions.
-/// </summary>
-public enum GtkFileChooserAction
-{
-    Open = 0,
-    Save = 1,
-    SelectFolder = 2,
-    CreateFolder = 3
-}
-
-/// <summary>
-/// Result from a file dialog.
-/// </summary>
-public class FileDialogResult
-{
-    public bool Accepted { get; init; }
-    public string[] SelectedFiles { get; init; } = Array.Empty<string>();
-    public string? SelectedFile => SelectedFiles.Length > 0 ? SelectedFiles[0] : null;
-}
-
-/// <summary>
-/// Result from a color dialog.
-/// </summary>
-public class ColorDialogResult
-{
-    public bool Accepted { get; init; }
-    public float Red { get; init; }
-    public float Green { get; init; }
-    public float Blue { get; init; }
-    public float Alpha { get; init; }
-}
-
-/// <summary>
-/// GTK4 interop layer for native Linux dialogs.
-/// Provides native file pickers, message boxes, and color choosers.
-/// </summary>
 public class Gtk4InteropService : IDisposable
 {
     #region GTK4 Native Interop