update greeting

lib/services/message_service.dart

@@ -34,16 +34,7 @@ class MessageService extends ChangeNotifier {
       TextClassificationService();
   final VehicleCommandService _vehicleCommandService = VehicleCommandService();
 
-  final List<ChatMessage> _messages = [
-    ChatMessage(
-        id: Uuid().v1(),
-        text: Intl.getCurrentLocale().startsWith('zh')
-            ? "您好，我是众众，请问有什么可以帮您？"
-            : "Hi, I'm Zhongzhong, may I help you ? ",
-        isUser: false,
-        timestamp: DateTime.now(),
-        status: MessageStatus.normal)
-  ];
+  final List<ChatMessage> _messages = [];
 
   List<ChatMessage> get messages => List.unmodifiable(_messages);
 
@@ -62,6 +53,11 @@ class MessageService extends ChangeNotifier {
 
   bool _isReplyAborted = true;
 
+  void initializeEmpty() {
+    _messages.clear();
+    notifyListeners();
+  }
+
   Future<void> startVoiceInput() async {
     if (await Permission.microphone.status == PermissionStatus.denied) {
       PermissionStatus status = await Permission.microphone.request();