Initial commit: RustDesk 1.4.7 macOS desktop port

- Filled empty libs/hbb_common/ submodule (cloned from rustdesk/hbb_common)
- Patched Flutter 3.44 / Dart 3.12 compatibility:
  * flutter/lib/generated_bridge.dart: asTypedList with cast<>, DartPort=Int64
  * flutter/lib/common.dart: DialogTheme->DialogThemeData, TabBarTheme->TabBarThemeData
  * flutter/pubspec.yaml: extended_text 14.0.0->15.0.2, google_fonts override 5.0.0
  * flutter/macos/Runner/Configs/Release.xcconfig: EXCLUDED_ARCHS=x86_64
- Build verified: cargo check + cargo build --features flutter + cargo build --release --features flutter
- Verified flutter build macos --debug and --release both produce working .app
- Verified .dmg installer (27MB arm64) created via hdiutil
- Build deps: Xcode 26.5, CocoaPods 1.16.2, Flutter 3.44, VCPKG arm64-osx

flutter/linux/bump_mouse_x11.cc

@@ -0,0 +1,30 @@
+#include "bump_mouse.h"
+
+#include <gtk/gtk.h>
+
+#include <gdk/gdkx.h>
+
+#include <iostream>
+
+bool bump_mouse_x11(int dx, int dy)
+{
+  GdkDevice *mouse_device;
+
+#if GTK_CHECK_VERSION(3, 20, 0)
+  auto seat = gdk_display_get_default_seat(gdk_display_get_default());
+
+  mouse_device = gdk_seat_get_pointer(seat);
+#else
+  auto devman = gdk_display_get_device_manager(gdk_display_get_default());
+
+  mouse_device = gdk_device_manager_get_client_pointer(devman);
+#endif
+
+  GdkScreen *screen;
+  gint x, y;
+
+  gdk_device_get_position(mouse_device, &screen, &x, &y);
+  gdk_device_warp(mouse_device, screen, x + dx, y + dy);
+
+  return true;
+}