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/portal.test.js

@@ -353,6 +353,19 @@ async function buildApp(options = {}) {
 }
 
 describe("portal routes", () => {
+
+  it("returns the registered disabled reason without changing the portal gate", async () => {
+    featureFlagState.portalHome = false;
+    const { app, prisma } = await buildApp();
+    try {
+      const response = await app.inject({ method: "GET", url: "/api/portal/home", headers: { authorization: "Bearer synthetic" } });
+      expect(response.statusCode).toBe(409);
+      expect(response.json().error.code).toBe("VALID_001");
+      expect(response.json().error.details).toMatchObject({ reasonCode: "portal.disabled", featureFlag: "portal_home_v1_disabled" });
+      const businessCalls = Object.entries(prisma).filter(([name]) => name !== "featureFlag").flatMap(([, model]) => Object.values(model ?? {})).filter(vi.isMockFunction);
+      expect(businessCalls.every((fn) => fn.mock.calls.length === 0)).toBe(true);
+    } finally { await app.close(); }
+  });
   beforeEach(() => {
     vi.useFakeTimers();
     vi.setSystemTime(new Date("2026-04-12T02:00:00.000Z"));