fix: 修复员工服务、报销单审批及前端交互细节

- 修复员工创建时组织架构关联与邮箱校验逻辑
- 修复报销单API端点参数及预审流程调用
- 优化审批中心、差旅详情等前端页面交互
- 更新侧边栏导航与请求视图模型
- 补充员工服务与报销单相关测试用例

server/tests/test_expense_claim_service.py

@@ -1312,7 +1312,7 @@ def test_privileged_user_can_return_and_delete_submitted_claim() -> None:
 
         assert returned is not None
         assert returned.status == "returned"
-        assert returned.approval_stage == "待补充"
+        assert returned.approval_stage == "待提交"
         assert any(
             isinstance(flag, dict)
             and flag.get("source") == "manual_return"