test(business): 业务数据管理模块集成用例（70 例）与两处缺陷修复

- 覆盖：编号格式与序号递增/状态机终态拦截/三处汇总冗余一致性/跨业务批次
  400/已核算禁改禁删/毛利润金标准与防除零/asOf 回溯/评级重叠/审计双记录
- 缺陷修复①：change_status 留痕 old_status 取到赋值后属性（时间线失真 3→3）
- 缺陷修复②：freight_amount 漏金额校验（负数/三位小数可落库污染运费合计）
- conftest 扩展业务六表清理（编号前缀 + FK 逆序收口）与评级种子基线恢复
- 全量回归 603 passed（单元 381 / 集成 222）

Co-Authored-By: Claude Code <noreply@anthropic.com>

backend/tests/integration/conftest.py

@@ -12,9 +12,15 @@
   消失，必须显式清理，否则残留会影响后续用例对留痕条数的断言
 - 操作日志的清理同时按 username 与 user_id —— 账号被删除后其 ``user_id``
   会被 SET NULL，只能靠冗余的 username 追溯，清理逻辑必须覆盖两种状态
+- M2 业务数据（业务/发货/回款）单据编号由系统生成（YW/SH/HK 前缀 + 当日
+  序号），**没有 t_ 前缀可用**，兜底清理按编号前缀全量清（三类单据表目前
+  只有测试会写）；外键均为 RESTRICT，删除顺序不能倒，且必须在客户/人员
+  清理之前（FK 会挡住删客户/删人员）；评级判定表则恢复种子基线 ——
+  评级用例会删改种子构造重叠/相邻场景，恢复保证跨文件幂等
 """
 
 import uuid
+from decimal import Decimal
 
 import pytest
 from sqlalchemy import delete, select, update
@@ -23,18 +29,35 @@ from app.core.constants import ROLE_ADMIN, ROLE_USER
 from app.core.db import get_session_factory
 from app.core.security import create_access_token, hash_password
 from app.models import (
+    Business,
+    BusinessItem,
     BusinessRole,
+    BusinessStatusLog,
     Customer,
+    CustomerRatingGrade,
     OperationLog,
     OwnershipChangeLog,
     Personnel,
     PersonnelPlan,
     PersonnelRegion,
     Product,
+    Receipt,
     Role,
+    Shipment,
+    ShipmentItem,
     User,
     UserRole,
 )
+from app.models.customer import OWNER_TYPE_BUSINESS
+
+# 评级判定表的种子基线（与 db/migration/V5 一致）：判定按 sort_order 升序
+# 取首个 min_score ≤ 总分的等级，种子铺满 0-100
+_RATING_SEEDS = [
+    ("A", Decimal("90"), Decimal("100"), 1, "优秀"),
+    ("B", Decimal("75"), Decimal("89"), 2, "良好"),
+    ("C", Decimal("60"), Decimal("74"), 3, "合格"),
+    ("D", Decimal("0"), Decimal("59"), 4, "待改进"),
+]
 
 TEST_PASSWORD = "TestPwd@2026"
 # 模块级预计算一次：bcrypt（rounds=12）单次约 0.2–0.4 秒，逐用例重复哈希
@@ -69,6 +92,44 @@ def _purge_test_data() -> None:
             session.execute(delete(UserRole).where(UserRole.role_id.in_(role_ids)))
             session.execute(delete(Role).where(Role.id.in_(role_ids)))
 
+        # ---- M2 业务数据（T11）：业务/发货/回款三类单据 ----
+        # 编号系统生成、无 t_ 前缀可用，按业务编号前缀全量清（三类单据表目前
+        # 只有测试会写）。外键均为 RESTRICT，删除顺序不能倒：回款 → 发货
+        # 明细 → 发货单 → 业务明细 → 状态留痕 → 业务维度归属留痕（无外键，
+        # 须显式清）→ 业务主表；且必须在下方客户/人员清理之前，否则 FK 挡住
+        # 删客户/删人员（businesses.customer_id / .owner_personnel_id RESTRICT）
+        business_ids = list(
+            session.execute(select(Business.id).where(Business.business_no.like("YW%"))).scalars()
+        )
+        shipment_ids = list(
+            session.execute(select(Shipment.id).where(Shipment.shipment_no.like("SH%"))).scalars()
+        )
+        if business_ids:
+            session.execute(delete(Receipt).where(Receipt.business_id.in_(business_ids)))
+        if shipment_ids:
+            session.execute(delete(ShipmentItem).where(ShipmentItem.shipment_id.in_(shipment_ids)))
+            session.execute(delete(Shipment).where(Shipment.id.in_(shipment_ids)))
+        if business_ids:
+            session.execute(delete(BusinessItem).where(BusinessItem.business_id.in_(business_ids)))
+            session.execute(
+                delete(BusinessStatusLog).where(BusinessStatusLog.business_id.in_(business_ids))
+            )
+            session.execute(
+                delete(OwnershipChangeLog).where(
+                    OwnershipChangeLog.owner_type == OWNER_TYPE_BUSINESS,
+                    OwnershipChangeLog.business_id.in_(business_ids),
+                )
+            )
+            session.execute(delete(Business).where(Business.id.in_(business_ids)))
+
+        # 评级判定表恢复种子基线：评级用例会删改种子构造重叠/相邻场景，
+        # 兜底恢复保证每个用例开始时都是纯种子（判定表无下游引用，全删全插安全）
+        session.execute(delete(CustomerRatingGrade))
+        session.add_all(
+            CustomerRatingGrade(grade_name=n, min_score=lo, max_score=hi, sort_order=so, remark=rm)
+            for n, lo, hi, so, rm in _RATING_SEEDS
+        )
+
         # ---- M2 基础数据：客户/归属留痕/人员/产品/测试岗位 ----
         # 外键均为 RESTRICT，删除顺序不能倒：留痕无外键先按 customer_id 清，
         # 再删客户（子表）→ 人员（先置空 manager_id 自引用、清子表）→ 产品