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

docs/CONTRIBUTING-PL.md

@@ -0,0 +1,45 @@
+# Współtworzenie RustDesk
+
+RustDesk z zadowoleniem przyjmuje wkład od każdego. Oto wytyczne, jeśli chcesz nam pomóc:
+
+## Współtwórcy
+
+Contributions to RustDesk or its dependencies should be made in the form of GitHub
+pull requests. Each pull request will be reviewed by a core contributor
+(someone with permission to land patches) and either landed in the main tree or
+given feedback for changes that would be required. All contributions should
+follow this format, even those from core contributors.
+
+Should you wish to work on an issue, please claim it first by commenting on
+the GitHub issue that you want to work on it. This is to prevent duplicated
+efforts from contributors on the same issue.
+
+## Pull Request Checklist
+
+- Branch from the master branch and, if needed, rebase to the current master
+  branch before submitting your pull request. If it doesn't merge cleanly with
+  master you may be asked to rebase your changes.
+
+- Commits should be as small as possible, while ensuring that each commit is
+  correct independently (i.e., each commit should compile and pass tests).
+
+- Commits should be accompanied by a Developer Certificate of Origin
+  (http://developercertificate.org) sign-off, which indicates that you (and
+  your employer if applicable) agree to be bound by the terms of the
+  [project license](../LICENCE). In git, this is the `-s` option to `git commit`
+
+- If your patch is not getting reviewed or you need a specific person to review
+  it, you can @-reply a reviewer asking for a review in the pull request or a
+  comment, or you can ask for a review via [email](mailto:info@rustdesk.com).
+
+- Add tests relevant to the fixed bug or new feature.
+
+For specific git instructions, see [GitHub workflow 101](https://github.com/servo/servo/wiki/GitHub-workflow).
+
+## Kodeks postępowania
+
+[Kodeks postępowania](CODE_OF_CONDUCT-PL.md)
+
+## Komunikacja
+
+RustDesk contributors frequent the [Discord](https://discord.gg/nDceKgxnkV).