完善借款、编号、付款与预算并发及验收（09-06-release-gate-integrity）

汇总已落盘的借款本金与还款、兼容历史编号的周期化编号、付款责任与回单核验、报销进度和排序、PWA/采购事务、错误原因与日期校验及ERP退役。
统一共享预算池锁序和锁后判断，恢复差旅原预算选择，补原因码固定夹具及反向完整性检查。
纳入配套迁移、测试、受管QA、分层验收合同、规约及任务记录；原始证据留在ignored artifacts。

关联任务：09-17-company-loan-principal-repayment、09-17-erp-exclusive-retirement、09-18-reimbursement-periodic-numbering、09-08-reimbursement-payment-closeout、09-18-local-concurrency-product-fixes、09-19-budget-pool-concurrency、09-05-error-explainability-payment-readiness。
预算补审由Claude定向验证2文件928项通过，原4446/28及r6结果仍仅对应各自历史输入；本轮未重跑测试。
完整新候选门禁、R1真实入口接入与12项公网义务仍开放。生产编号未启用、差旅仍冻结；不推送、不部署，不宣称发布资格。

server/tests/unit/routes/expenseStandards.test.js

@@ -342,7 +342,7 @@ describe("expense standards routes", () => {
     });
 
     expect(response.statusCode).toBe(409);
-    expect(response.json().error.details).toEqual({ expenseTypeId: "not_found" });
+    expect(response.json().error.details).toEqual({ expenseTypeId: "not_found", reasonCode: "expense_standard.expense_type_not_found" });
 
     await app.close();
   });
@@ -362,7 +362,7 @@ describe("expense standards routes", () => {
     });
 
     expect(response.statusCode).toBe(400);
-    expect(response.json().error.details).toEqual({ scopeKey: "required_for_department_scope" });
+    expect(response.json().error.details).toEqual({ scopeKey: "required_for_department_scope", reasonCode: "expense_standard.department_required" });
 
     await app.close();
   });
@@ -381,7 +381,7 @@ describe("expense standards routes", () => {
     });
 
     expect(response.statusCode).toBe(409);
-    expect(response.json().error.details).toEqual({ duplicate: "expense_type_scope_conflict" });
+    expect(response.json().error.details).toEqual({ duplicate: "expense_type_scope_conflict", reasonCode: "expense_standard.scope_conflict" });
 
     await app.close();
   });