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>

Hosting/LinuxViewRenderer.cs

@@ -476,22 +476,3 @@ public class LinuxViewRenderer
     }
 }
 
-/// <summary>
-/// Extension methods for MAUI handler creation.
-/// </summary>
-public static class MauiHandlerExtensions
-{
-    /// <summary>
-    /// Creates a handler for the view and returns it.
-    /// </summary>
-    public static IElementHandler ToHandler(this IElement element, IMauiContext mauiContext)
-    {
-        var handler = mauiContext.Handlers.GetHandler(element.GetType());
-        if (handler != null)
-        {
-            handler.SetMauiContext(mauiContext);
-            handler.SetVirtualView(element);
-        }
-        return handler!;
-    }
-}