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/service/WebSocketService.java

@@ -27,13 +27,13 @@ public class WebSocketService {
     private SimpMessagingTemplate messagingTemplate;
 
     @Autowired
-    private IAiService aiService;
+    private AIChatService aiChatService;
 
     @Autowired
-    private IMessageService messageService;
+    private MessageService messageService;
 
     @Autowired
-    private IConversationService conversationService;
+    private ConversationService conversationService;
     
     // 在线用户管理
     private final ConcurrentHashMap<String, String> onlineUsers = new ConcurrentHashMap<>();
@@ -192,15 +192,17 @@ public class WebSocketService {
         new Thread(() -> {
             try {
                 // 保存用户消息到数据库
-                messageService.saveMessage(
+                messageService.createMessage(
                     request.getConversationId(),
-                    request.getContent(),
+                        request.getSenderId(),
+                            request.getContent(),
                     request.getMessageType().name(),
-                    request.getSenderType().name()
+                        request.getSenderType().name(),
+                        request.getSenderId()
                 );
 
                 // 调用AI服务
-                String aiReply = aiService.sendChatMessage(
+                String aiReply = aiChatService.sendChatMessage(
                     request.getConversationId(),
                     request.getContent(),
                     request.getSenderId()
@@ -219,11 +221,13 @@ public class WebSocketService {
                         .build();
                 
                 // 保存AI回复到数据库
-                messageService.saveMessage(
+                messageService.createMessage(
                     request.getConversationId(),
-                    aiReply,
+                        "ai",
+                            aiReply,
                     "text",
-                    "assistant"
+                        "ai",
+                        "ai"
                 );
 
                 // 发送AI回复