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/models/printer_model.dart

@@ -0,0 +1,48 @@
+import 'package:flutter_hbb/common.dart';
+import 'package:flutter_hbb/consts.dart';
+import 'package:flutter_hbb/models/platform_model.dart';
+
+class PrinterOptions {
+  String action;
+  List<String> printerNames;
+  String printerName;
+
+  PrinterOptions(
+      {required this.action,
+      required this.printerNames,
+      required this.printerName});
+
+  static PrinterOptions load() {
+    var action = bind.mainGetLocalOption(key: kKeyPrinterIncomingJobAction);
+    if (![
+      kValuePrinterIncomingJobDismiss,
+      kValuePrinterIncomingJobDefault,
+      kValuePrinterIncomingJobSelected
+    ].contains(action)) {
+      action = kValuePrinterIncomingJobDefault;
+    }
+
+    final printerNames = getPrinterNames();
+    var selectedPrinterName = bind.mainGetLocalOption(key: kKeyPrinterSelected);
+    if (!printerNames.contains(selectedPrinterName)) {
+      if (action == kValuePrinterIncomingJobSelected) {
+        action = kValuePrinterIncomingJobDefault;
+        bind.mainSetLocalOption(
+            key: kKeyPrinterIncomingJobAction,
+            value: kValuePrinterIncomingJobDefault);
+        if (printerNames.isEmpty) {
+          selectedPrinterName = '';
+        } else {
+          selectedPrinterName = printerNames.first;
+        }
+        bind.mainSetLocalOption(
+            key: kKeyPrinterSelected, value: selectedPrinterName);
+      }
+    }
+
+    return PrinterOptions(
+        action: action,
+        printerNames: printerNames,
+        printerName: selectedPrinterName);
+  }
+}