refactor(service): 统一Service缓存为VO对象并优化关联实体处理

重构Service类实现，将QueryService泛型参数调整为VO类型，确保缓存VO对象而非实体。优化关联实体处理逻辑，减少重复代码。修改findById方法返回VO对象，新增getById方法获取实体。更新相关调用点以适配新接口。

调整WebSocket处理、控制器及Service实现，确保数据类型一致性。完善文档记录重构过程及发现的问题。为后续优化提供基础架构支持。

server/src/main/java/com/ecep/contract/config/SecurityConfig.java

@@ -27,6 +27,7 @@ import org.springframework.security.web.SecurityFilterChain;
 import com.ecep.contract.ds.other.service.EmployeeService;
 import com.ecep.contract.model.Employee;
 import com.ecep.contract.model.EmployeeRole;
+import com.ecep.contract.vo.EmployeeVo;
 
 /**
  * Spring Security配置类
@@ -110,13 +111,16 @@ public class SecurityConfig {
     public UserDetailsService userDetailsService() {
         return username -> {
             // 使用EmployeeService根据用户名查找员工
-            Employee employee = employeeService.findByAccount(username);
+            EmployeeVo employeeVo = employeeService.findByAccount(username);
 
             // 如果找不到员工，抛出UsernameNotFoundException异常
-            if (employee == null) {
+            if (employeeVo == null) {
                 throw new UsernameNotFoundException("用户不存在: " + username);
             }
 
+            // 获取员工实体
+            Employee employee = employeeService.getById(employeeVo.getId());
+
             // 检查员工是否活跃
             if (!employee.isActive()) {
                 throw new UsernameNotFoundException("用户已禁用: " + username);