feat: 完善审批退回流程与报销申请关联

后端优化报销单访问策略和常量定义，增强退回原因和审批状态
流转，前端完善退回对话框和审批交互组件，新增报销申请关联
模型，优化文档中心行数据和审批收件箱工具函数，增强引导
流程和会话模型，补充单元测试覆盖。

web/tests/travel-request-detail-risk-advice.test.mjs

@@ -678,10 +678,21 @@ test('transport ticket items no longer generate business location completion adv
 test('return reason dialog is wired into approval and detail return actions', () => {
   assert.match(returnReasonDialog, /missing_attachment/)
   assert.match(returnReasonDialog, /invoice_mismatch/)
+  assert.match(returnReasonDialog, /APPLICATION_RETURN_REASON_OPTIONS/)
+  assert.match(returnReasonDialog, /application_info_incomplete/)
+  assert.match(returnReasonDialog, /application_business_need_unclear/)
+  assert.match(returnReasonDialog, /application_budget_basis_missing/)
+  assert.match(returnReasonDialog, /application_policy_mismatch/)
+  assert.match(returnReasonDialog, /application_attachment_needed/)
+  assert.match(returnReasonDialog, /退单选项/)
+  assert.match(returnReasonDialog, /selectionError/)
+  assert.match(returnReasonDialog, /selectedCodes\.value\.length === 0/)
+  assert.match(returnReasonDialog, /lastAutoReason/)
   assert.match(returnReasonDialog, /reason_codes/)
   assert.match(approvalCenterTemplate, /<TravelRequestDetailView/)
   assert.doesNotMatch(approvalCenterTemplate, /<ReturnReasonDialog/)
-  assert.match(detailViewTemplate, /<ReturnReasonDialog/)
+  assert.match(detailViewTemplate, /<TravelRequestReturnDialog/)
+  assert.match(detailViewTemplate, /:application="isApplicationDocument"/)
   assert.doesNotMatch(approvalCenterScript, /returnExpenseClaim/)
   assert.match(detailViewScript, /returnExpenseClaim\(request\.value\.claimId, payload\)/)
   assert.doesNotMatch(approvalCenterScript, /审批中心退回/)