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/config/RestTemplateConfig.java

@@ -0,0 +1,13 @@
+package com.emotion.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.client.RestTemplate;
+
+@Configuration
+public class RestTemplateConfig {
+    @Bean
+    public RestTemplate restTemplate() {
+        return new RestTemplate();
+    }
+}