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

libs/hbb_common/src/platform/macos.rs

@@ -0,0 +1,55 @@
+use crate::ResultType;
+use osascript;
+use serde_derive::{Deserialize, Serialize};
+
+#[derive(Serialize)]
+struct AlertParams {
+    title: String,
+    message: String,
+    alert_type: String,
+    buttons: Vec<String>,
+}
+
+#[derive(Deserialize)]
+struct AlertResult {
+    #[serde(rename = "buttonReturned")]
+    button: String,
+}
+
+/// Firstly run the specified app, then alert a dialog. Return the clicked button value.
+///
+/// # Arguments
+///
+/// * `app` - The app to execute the script.
+/// * `alert_type` - Alert type. . informational, warning, critical
+/// * `title` - The alert title.
+/// * `message` - The alert message.
+/// * `buttons` - The buttons to show.
+pub fn alert(
+    app: String,
+    alert_type: String,
+    title: String,
+    message: String,
+    buttons: Vec<String>,
+) -> ResultType<String> {
+    let script = osascript::JavaScript::new(&format!(
+        "
+    var App = Application('{}');
+    App.includeStandardAdditions = true;
+    return App.displayAlert($params.title, {{
+        message: $params.message,
+        'as': $params.alert_type,
+        buttons: $params.buttons,
+    }});
+    ",
+        app
+    ));
+
+    let result: AlertResult = script.execute_with_params(AlertParams {
+        title,
+        message,
+        alert_type,
+        buttons,
+    })?;
+    Ok(result.button)
+}