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/lib/native/win32.dart

@@ -0,0 +1,41 @@
+import 'dart:ffi' hide Size;
+
+import 'package:ffi/ffi.dart';
+
+import 'package:win32/win32.dart' as win32;
+
+/// Get windows target build number.
+///
+/// [Note]
+/// Please use this function wrapped with `Platform.isWindows`.
+int getWindowsTargetBuildNumber_() {
+  final rtlGetVersion = DynamicLibrary.open('ntdll.dll').lookupFunction<
+      Void Function(Pointer<win32.OSVERSIONINFOEX>),
+      void Function(Pointer<win32.OSVERSIONINFOEX>)>('RtlGetVersion');
+  final osVersionInfo = _getOSVERSIONINFOEXPointer();
+  rtlGetVersion(osVersionInfo);
+  int buildNumber = osVersionInfo.ref.dwBuildNumber;
+  calloc.free(osVersionInfo);
+  return buildNumber;
+}
+
+/// Get Windows OS version pointer
+///
+/// [Note]
+/// Please use this function wrapped with `Platform.isWindows`.
+Pointer<win32.OSVERSIONINFOEX> _getOSVERSIONINFOEXPointer() {
+  final pointer = calloc<win32.OSVERSIONINFOEX>();
+  pointer.ref
+    ..dwOSVersionInfoSize = sizeOf<win32.OSVERSIONINFOEX>()
+    ..dwBuildNumber = 0
+    ..dwMajorVersion = 0
+    ..dwMinorVersion = 0
+    ..dwPlatformId = 0
+    ..szCSDVersion = ''
+    ..wServicePackMajor = 0
+    ..wServicePackMinor = 0
+    ..wSuiteMask = 0
+    ..wProductType = 0
+    ..wReserved = 0;
+  return pointer;
+}