feat: 完善芽说英语品牌Logo与图标配置，完成跨平台云端同步服务开发与自动化部署

kouyu_english/lib/core/models.dart

@@ -81,10 +81,12 @@ class DialogueAiResponse {
     required this.slots,
     required this.evidence,
     required this.suggestsComplete,
+    this.translation,
     this.feedback,
   });
 
   final String reply;
+  final String? translation;
   final Map<String, String> slots;
   final List<String> evidence;
   final bool suggestsComplete;
@@ -297,10 +299,27 @@ class MasteryItem {
 }
 
 class DialogueTurn {
-  const DialogueTurn({required this.text, required this.isLearner});
+  const DialogueTurn({
+    required this.text,
+    required this.isLearner,
+    this.translation,
+  });
 
   final String text;
   final bool isLearner;
+  final String? translation;
+
+  DialogueTurn copyWith({
+    String? text,
+    bool? isLearner,
+    String? translation,
+  }) {
+    return DialogueTurn(
+      text: text ?? this.text,
+      isLearner: isLearner ?? this.isLearner,
+      translation: translation ?? this.translation,
+    );
+  }
 }
 
 /// Ephemeral presentation data for a completed controlled dialogue. The