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/prisma/migrations/20260918160000_business_numbering/migration.sql

@@ -0,0 +1,51 @@
+-- Additive only: existing identifiers and both old counters and drafts stay intact.
+CREATE TABLE "business_number_policies" (
+  "version" INTEGER PRIMARY KEY CHECK ("version" = 2),
+  "effective_at" TIMESTAMP(3) NOT NULL,
+  "enabled" BOOLEAN NOT NULL DEFAULT false,
+  "updated_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  "updated_by" UUID NOT NULL,
+  "reference" TEXT NOT NULL
+);
+CREATE TABLE "business_number_counters" (
+  "key" TEXT PRIMARY KEY,
+  "current_number" BIGINT NOT NULL DEFAULT 0 CHECK ("current_number" >= 0),
+  "updated_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+ALTER TABLE "purchase_requests" ADD COLUMN "numbering_version" INTEGER NOT NULL DEFAULT 1
+  CHECK ("numbering_version" IN (1, 2));
+-- No INSERT into policy; activation is a separate, explicitly authorized operation.
+
+-- Keep the original eligibility and issued high-water durable across rollback or
+-- accidental administrative resets. A pause changes only policy.enabled.
+CREATE FUNCTION guard_business_numbering_history() RETURNS trigger AS $$
+BEGIN
+  IF TG_OP = 'DELETE' THEN
+    RAISE EXCEPTION 'business numbering history cannot be deleted' USING ERRCODE = '23514';
+  END IF;
+  IF TG_TABLE_NAME = 'business_number_policies' THEN
+    IF NEW.version <> OLD.version OR NEW.effective_at <> OLD.effective_at THEN
+      RAISE EXCEPTION 'business numbering activation is immutable' USING ERRCODE = '23514';
+    END IF;
+  ELSIF TG_TABLE_NAME = 'business_number_counters' THEN
+    IF NEW.key <> OLD.key OR NEW.current_number < OLD.current_number THEN
+      RAISE EXCEPTION 'business numbering high-water cannot decrease' USING ERRCODE = '23514';
+    END IF;
+  END IF;
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+CREATE TRIGGER business_number_policy_history BEFORE UPDATE OR DELETE ON business_number_policies
+  FOR EACH ROW EXECUTE FUNCTION guard_business_numbering_history();
+CREATE TRIGGER business_number_counter_history BEFORE UPDATE OR DELETE ON business_number_counters
+  FOR EACH ROW EXECUTE FUNCTION guard_business_numbering_history();
+CREATE FUNCTION guard_purchase_numbering_version() RETURNS trigger AS $$
+BEGIN
+  IF NEW.numbering_version <> OLD.numbering_version THEN
+    RAISE EXCEPTION 'purchase numbering eligibility is immutable' USING ERRCODE = '23514';
+  END IF;
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+CREATE TRIGGER purchase_numbering_version BEFORE UPDATE OF numbering_version ON purchase_requests
+  FOR EACH ROW EXECUTE FUNCTION guard_purchase_numbering_version();