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/payroll.salary-profile.test.js

@@ -234,3 +234,47 @@ describe("payroll salary profile routes", () => {
     await app.close();
   });
 });
+
+describe("salary profile calendar boundary", () => {
+  it.each(["2024-02-29", "2026-04-30"])("stores exact effectiveDate %s", async (effectiveDate) => {
+    const { app, state, employeeSalary } = await buildApp();
+    try {
+      const response = await app.inject({ method: "PUT", url: `/api/payroll/employees/${EMPLOYEE_ID}/profile`, payload: { effectiveDate, items: [{ salaryItemId: state.salaryItems[0].id, monthlyAmount: "100.00" }] } });
+      expect(response.statusCode).toBe(200);
+      expect(employeeSalary.createMany.mock.calls[0][0].data[0].effective_date.toISOString()).toBe(`${effectiveDate}T00:00:00.000Z`);
+    } finally { await app.close(); }
+  });
+});
+
+describe("salary profile reasons", () => {
+  it.each([
+    [{ effectiveDate: "2026-02-30", items: [] }, "payroll.profile_input_invalid"],
+    [{ effectiveDate: "2026-04-01", items: [{ salaryItemId: "11111111-1111-4111-8111-111111111111", monthlyAmount: "1.234" }] }, "payroll.amount_invalid"],
+    [{ effectiveDate: "2026-04-01", items: [{ salaryItemId: "11111111-1111-4111-8111-111111111111", monthlyAmount: -1 }] }, "payroll.amount_invalid"],
+  ])("explains invalid profile %j", async (payload, reasonCode) => {
+    const { app } = await buildApp();
+    try {
+      const response = await app.inject({ method: "PUT", url: `/api/payroll/employees/${EMPLOYEE_ID}/profile`, payload });
+      expect(response.statusCode).toBe(400);
+      expect(response.json().error.details.reasonCode).toBe(reasonCode);
+      if (reasonCode === "payroll.amount_invalid") expect(response.json().error.details).toEqual({ items: { 0: { monthlyAmount: "invalid_money_amount" } }, reasonCode });
+      expect(app.prisma.employee.findUnique).not.toHaveBeenCalled();
+      expect(app.prisma.employeeSalary.deleteMany).not.toHaveBeenCalled();
+      expect(app.prisma.employeeSalary.createMany).not.toHaveBeenCalled();
+      expect(app.prisma.auditLog.create).not.toHaveBeenCalled();
+      expect(app.prisma.$transaction).not.toHaveBeenCalled();
+    } finally { await app.close(); }
+  });
+  it("explains unavailable salary items before replacing a snapshot", async () => {
+    const { app } = await buildApp();
+    app.prisma.salaryItem.findMany.mockResolvedValueOnce([]);
+    try {
+      const response = await app.inject({ method: "PUT", url: `/api/payroll/employees/${EMPLOYEE_ID}/profile`, payload: { effectiveDate: "2026-04-01", items: [{ salaryItemId: "11111111-1111-4111-8111-111111111111", monthlyAmount: 100 }] } });
+      expect(response.statusCode).toBe(400);
+      expect(response.json().error.details).toEqual({ items: "salary_item_not_found", reasonCode: "payroll.item_not_found" });
+      expect(app.prisma.$transaction).not.toHaveBeenCalled();
+      expect(app.prisma.employeeSalary.deleteMany).not.toHaveBeenCalled();
+      expect(app.prisma.auditLog.create).not.toHaveBeenCalled();
+    } finally { await app.close(); }
+  });
+});