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>

Handlers/BorderHandler.cs

@@ -5,6 +5,7 @@ using Microsoft.Maui.Handlers;
 using Microsoft.Maui.Graphics;
 using Microsoft.Maui.Controls;
 using Microsoft.Maui.Platform;
+using Microsoft.Maui.Platform.Linux.Hosting;
 using SkiaSharp;
 
 namespace Microsoft.Maui.Platform.Linux.Handlers;
@@ -68,7 +69,7 @@ public partial class BorderHandler : ViewHandler<IBorderView, SkiaBorder>
             if (content.Handler == null)
             {
                 Console.WriteLine($"[BorderHandler] Creating handler for content: {content.GetType().Name}");
-                content.Handler = content.ToHandler(handler.MauiContext);
+                content.Handler = content.ToViewHandler(handler.MauiContext);
             }
 
             if (content.Handler?.PlatformView is SkiaView skiaContent)