Major production merge: GTK support, context menus, and dispatcher fixes

Core Infrastructure:
- Add Dispatching folder with LinuxDispatcher, LinuxDispatcherProvider, LinuxDispatcherTimer
- Add Native folder with P/Invoke wrappers (GTK, GLib, GDK, Cairo, WebKit)
- Add GTK host window system with GtkHostWindow and GtkSkiaSurfaceWidget
- Update LinuxApplication with GTK mode, theme handling, and icon support
- Fix duplicate LinuxDispatcher in LinuxMauiContext

Handlers:
- Add GtkWebViewManager and GtkWebViewPlatformView for GTK WebView
- Add FlexLayoutHandler and GestureManager
- Update multiple handlers with ToViewHandler fix and missing mappers
- Add MauiHandlerExtensions with ToViewHandler extension method

Views:
- Add SkiaContextMenu with hover, keyboard, and dark theme support
- Add LinuxDialogService with context menu management
- Add SkiaFlexLayout for flex container support
- Update SkiaShell with RefreshTheme, MauiShell, ContentRenderer
- Update SkiaWebView with SetMainWindow, ProcessGtkEvents
- Update SkiaImage with LoadFromBitmap method

Services:
- Add AppInfoService, ConnectivityService, DeviceDisplayService, DeviceInfoService
- Add GtkHostService, GtkContextMenuService, MauiIconGenerator

Window:
- Add CursorType enum and GtkHostWindow
- Update X11Window with SetIcon, SetCursor methods

Build: SUCCESS (0 errors)

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

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

Views/SkiaAlertDialog.cs

@@ -323,63 +323,3 @@ public class SkiaAlertDialog : SkiaView
         return this;
     }
 }
-
-/// <summary>
-/// Service for showing modal dialogs in OpenMaui Linux.
-/// </summary>
-public static class LinuxDialogService
-{
-    private static readonly List<SkiaAlertDialog> _activeDialogs = new();
-    private static Action? _invalidateCallback;
-
-    /// <summary>
-    /// Registers the invalidation callback (called by LinuxApplication).
-    /// </summary>
-    public static void SetInvalidateCallback(Action callback)
-    {
-        _invalidateCallback = callback;
-    }
-
-    /// <summary>
-    /// Shows an alert dialog and returns when dismissed.
-    /// </summary>
-    public static Task<bool> ShowAlertAsync(string title, string message, string? accept, string? cancel)
-    {
-        var dialog = new SkiaAlertDialog(title, message, accept, cancel);
-        _activeDialogs.Add(dialog);
-        _invalidateCallback?.Invoke();
-        return dialog.Result;
-    }
-
-    /// <summary>
-    /// Hides a dialog.
-    /// </summary>
-    internal static void HideDialog(SkiaAlertDialog dialog)
-    {
-        _activeDialogs.Remove(dialog);
-        _invalidateCallback?.Invoke();
-    }
-
-    /// <summary>
-    /// Gets whether there are active dialogs.
-    /// </summary>
-    public static bool HasActiveDialog => _activeDialogs.Count > 0;
-
-    /// <summary>
-    /// Gets the topmost dialog.
-    /// </summary>
-    public static SkiaAlertDialog? TopDialog => _activeDialogs.Count > 0 ? _activeDialogs[^1] : null;
-
-    /// <summary>
-    /// Draws all active dialogs.
-    /// </summary>
-    public static void DrawDialogs(SKCanvas canvas, SKRect bounds)
-    {
-        foreach (var dialog in _activeDialogs)
-        {
-            dialog.Measure(new SKSize(bounds.Width, bounds.Height));
-            dialog.Arrange(bounds);
-            dialog.Draw(canvas);
-        }
-    }
-}