feat(employee): 添加员工插入时的重复用户检查

- 实现用户ID存在性验证逻辑
- 防止重复插入相同用户ID的员工记录
- 添加运行时异常处理机制

klp-hrm/src/main/java/com/klp/hrm/service/impl/HrmEmployeeServiceImpl.java

@@ -45,6 +45,11 @@ public class HrmEmployeeServiceImpl implements IHrmEmployeeService {
     @Override
     @Transactional(rollbackFor = Exception.class)
     public Boolean insertByBo(HrmEmployeeBo bo) {
+        Long userId = bo.getUserId();
+        //        如果存在则不插入
+        if (baseMapper.exists(Wrappers.<HrmEmployee>lambdaQuery().eq(HrmEmployee::getUserId, userId))) {
+            throw new RuntimeException("用户已存在");
+        }
         HrmEmployee add = BeanUtil.toBean(bo, HrmEmployee.class);
         return baseMapper.insert(add) > 0;
     }