Update Android icons and enter action

lib/main.dart

@@ -123,6 +123,11 @@ class NativeConnectionApi {
     return result ?? false;
   }
 
+  Future<bool> sendEnter() async {
+    final result = await _methodChannel.invokeMethod<bool>('sendEnter');
+    return result ?? false;
+  }
+
   Future<List<DiscoveredDevice>> startDiscovery() async {
     try {
       final result = await _methodChannel.invokeListMethod<dynamic>(
@@ -341,15 +346,14 @@ class _InputSyncPageState extends State<InputSyncPage>
     }
 
     final draft = inputController.text;
-    final textToSend = appendEnter ? '$draft\n' : draft;
-
     setState(() {
       sendButtonState = SendButtonState.sending;
     });
 
     try {
-      final sent = await api.sendText(textToSend);
-      if (!sent) {
+      final sent = await api.sendText(draft);
+      final enterSent = !sent || !appendEnter ? true : await api.sendEnter();
+      if (!sent || !enterSent) {
         _showToast('发送失败，连接已断开');
         setState(() {
           sendButtonState = SendButtonState.idle;