isActivityRecognitionAvailable method
Checks if activity recognition is available
Implementation
@override
Future<bool> isActivityRecognitionAvailable() async {
  try {
    if (!Platform.isAndroid && !Platform.isIOS) {
      return false;
    }
    final bool? result = await _methodChannel.invokeMethod('isAvailable');
    return result ?? false;
  } on PlatformException catch (e) {
    if (kDebugMode) {
      print('Error checking availability: ${e.message}');
    }
    return false;
  }
}