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

res/vcpkg/ffmpeg/0007-fix-lib-naming.patch

@@ -0,0 +1,12 @@
+diff --git a/configure b/configure
+index d6c4388..75b96c3 100644
+--- a/configure
++++ b/configure
+@@ -4781,6 +4781,7 @@ msvc_common_flags(){
+             -mfp16-format=*)      ;;
+             -lz)                  echo zlib.lib ;;
+             -lx264)               echo libx264.lib ;;
++            -lmp3lame)            echo libmp3lame.lib ;;
+             -lstdc++)             ;;
+             -l*)                  echo ${flag#-l}.lib ;;
+             -LARGEADDRESSAWARE)   echo $flag ;;