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

.github/workflows/flutter-ci.yml

@@ -0,0 +1,24 @@
+name: Full Flutter CI
+
+on:
+  workflow_dispatch:
+  pull_request:
+    paths-ignore:
+    - "docs/**"
+    - "README.md"
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - ".github/**"
+      - "docs/**"
+      - "README.md"
+      - "res/**"
+      - "appimage/**"
+      - "flatpak/**"
+
+jobs:
+  run-ci:
+    uses: ./.github/workflows/flutter-build.yml
+    with:
+      upload-artifact: false