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/utils/workflow.test.js

@@ -453,3 +453,25 @@ describe("workflow assignee resolution", () => {
     ]);
   });
 });
+
+describe("workflow shared error reasons", () => {
+  function errorFrom(run) { try { run(); } catch (error) { return error; } throw new Error("expected rejection"); }
+  it.each([undefined, { steps: [] }, { steps: "bad" }])("explains invalid steps %s", (definition) => { expect(errorFrom(() => workflowUtils.parseWorkflowSteps(definition))).toMatchObject({ code: "VALID_001", statusCode: 400, details: { workflow: "invalid_steps", reasonCode: "workflow.steps_invalid" } }); });
+  it.each([[null, "approval_rule_invalid", "invalid_approval_rule"], [{}, "approval_chain_empty", "empty_approval_chain"], [{ level1_role: "admin" }, "business_role_unsupported", "unsupported_business_approval_role"]])("explains approval rule %s", (rule, reason, detail) => { expect(errorFrom(() => workflowUtils.buildWorkflowStepsFromApprovalRule(rule))).toMatchObject({ code: "VALID_001", statusCode: 400, details: { workflow: detail, reasonCode: `workflow.${reason}` } }); });
+  it.each([[null, {}, "assignee_rule_invalid", "invalid_assignee_rule"], [{ type: "role", value: "" }, {}, "role_assignee_invalid", "invalid_role_assignee"], [{ type: "role", value: "admin" }, {}, "business_role_unsupported", "unsupported_business_approval_role"], [{ type: "specific_user", value: "bad" }, {}, "user_assignee_invalid", "invalid_specific_user_assignee"], [{ type: "department_manager" }, {}, "manager_context_invalid", "invalid_department_manager_context"], [{ type: "unsupported" }, {}, "assignee_type_unsupported", "unsupported_assignee_rule_type"]])("explains assignee rule %s", async (rule, context, reason, detail) => { await expect(workflowUtils.resolveAssigneeFromRule(rule, context)).rejects.toMatchObject({ code: "VALID_001", statusCode: 400, details: { workflow: detail, reasonCode: `workflow.${reason}` } }); });
+  it.each([["hr", ["ceo"], true, "fallback_role_unsupported", 400, { ownerSelfFallbackRole: "unsupported_business_approval_role" }], ["finance", ["ceo", "finance"], true, "fallback_role_is_self", 409, { workflow: "no_actionable_approver", reason: "owner_self_fallback_self_role" }], ["finance", ["ceo"], false, "fallback_holder_unavailable", 409, { workflow: "no_actionable_approver", reason: "owner_self_fallback_role_unavailable", fallbackRole: "finance" }]])("explains fallback %s with roles %s", async (role, roles, available, reason, status, details) => {
+    const tx = buildTx({ ownerRoles: roles, fallbackHasHolder: available });
+    await expect(workflowUtils.buildApprovalWorkflowSnapshot({ tx, ownerId: OWNER_ID, approvalRule: { level1_role: "manager", owner_self_fallback_role: role } })).rejects.toMatchObject({ code: "VALID_001", statusCode: status, details: { reasonCode: `workflow.${reason}`, ...details } });
+    if (reason !== "fallback_holder_unavailable") expect(tx.employeeRole.findFirst).not.toHaveBeenCalled();
+  });
+  it.each([[null, "chain_broken"], [{ id: OWNER_ID, direct_manager_id: null }, "no_manager_found"], [{ id: OWNER_ID, direct_manager_id: OWNER_ID }, "self_loop"]])("explains blocked manager %s while preserving optional skip", async (row, reason) => {
+    const tx = { employee: { findUnique: vi.fn().mockResolvedValue(row) } };
+    const options = { tx, steps: buildSteps(), startIndex: 0, ownerId: OWNER_ID };
+    await expect(workflowUtils.resolveActionableStep({ ...options, blockOnUnresolvedAssignee: true })).rejects.toMatchObject({ code: "VALID_001", statusCode: 409, details: { workflow: "no_actionable_approver", reason, stepId: "approval_1_manager", reasonCode: "workflow.manager_unavailable" } });
+    const skipped = await workflowUtils.resolveActionableStep(options); expect(skipped.actionable.assigneeRole).toBe("finance"); expect(skipped.skipped[0].reason).toBe(reason);
+  });
+  it("preserves valid specific-user and historical snapshot selection", async () => {
+    await expect(workflowUtils.resolveAssigneeFromRule({ type: "specific_user", value: MANAGER_ID })).resolves.toMatchObject({ assigneeId: MANAGER_ID, assigneeRole: null });
+    const steps = buildSteps(); expect(workflowUtils.getWorkflowStepsSnapshot({ context_data: { workflow_steps_snapshot: steps }, definition: { definition_json: { steps: [{ id: "different" }] } } })).toEqual(steps);
+  });
+});