服务层重构与优化：补全所有ServiceImpl实现类，修复RestTemplate注入，完善DTO与配置，保证编译与启动通过

backend-single/src/main/java/com/emotion/controller/WebSocketController.java

@@ -1,6 +1,6 @@
 package com.emotion.controller;
 
-import com.emotion.service.AiService;
+import com.emotion.service.AIChatService;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -31,7 +31,7 @@ public class WebSocketController {
     private SimpMessagingTemplate messagingTemplate;
 
     @Autowired
-    private AiService aiService;
+    private AIChatService aiChatService;
 
     // 已移除旧的WebSocket消息处理方法，使用新的ChatWebSocketController
 
@@ -51,7 +51,7 @@ public class WebSocketController {
             String userId = (String) chatMessage.get("userId");
             
             // 调用AI服务
-            String aiReply = aiService.sendMessage(conversationId, content, userId);
+            String aiReply = aiChatService.sendMessage(conversationId, content, userId);
             
             // 构建AI回复消息
             Map<String, Object> aiResponse = new HashMap<>();