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>

Native/CairoNative.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Microsoft.Maui.Platform.Linux.Native;
+
+internal static class CairoNative
+{
+    public enum cairo_format_t
+    {
+        CAIRO_FORMAT_INVALID = -1,
+        CAIRO_FORMAT_ARGB32,
+        CAIRO_FORMAT_RGB24,
+        CAIRO_FORMAT_A8,
+        CAIRO_FORMAT_A1,
+        CAIRO_FORMAT_RGB16_565,
+        CAIRO_FORMAT_RGB30
+    }
+
+    private const string Lib = "libcairo.so.2";
+
+    [DllImport("libcairo.so.2")]
+    public static extern IntPtr cairo_image_surface_create_for_data(IntPtr data, cairo_format_t format, int width, int height, int stride);
+
+    [DllImport("libcairo.so.2")]
+    public static extern IntPtr cairo_image_surface_create(cairo_format_t format, int width, int height);
+
+    [DllImport("libcairo.so.2")]
+    public static extern IntPtr cairo_image_surface_get_data(IntPtr surface);
+
+    [DllImport("libcairo.so.2")]
+    public static extern int cairo_image_surface_get_width(IntPtr surface);
+
+    [DllImport("libcairo.so.2")]
+    public static extern int cairo_image_surface_get_height(IntPtr surface);
+
+    [DllImport("libcairo.so.2")]
+    public static extern int cairo_image_surface_get_stride(IntPtr surface);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_surface_destroy(IntPtr surface);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_surface_flush(IntPtr surface);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_surface_mark_dirty(IntPtr surface);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_surface_mark_dirty_rectangle(IntPtr surface, int x, int y, int width, int height);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_set_source_surface(IntPtr cr, IntPtr surface, double x, double y);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_set_source_rgb(IntPtr cr, double red, double green, double blue);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_set_source_rgba(IntPtr cr, double red, double green, double blue, double alpha);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_paint(IntPtr cr);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_paint_with_alpha(IntPtr cr, double alpha);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_fill(IntPtr cr);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_rectangle(IntPtr cr, double x, double y, double width, double height);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_clip(IntPtr cr);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_save(IntPtr cr);
+
+    [DllImport("libcairo.so.2")]
+    public static extern void cairo_restore(IntPtr cr);
+}