feat(business): 新增业务数据七表及 V5 迁移（业务/明细/状态留痕/发货/回款/评级配置）

- businesses 五项汇总冗余列服务层事务内维护；毛利润不落库（派生值，M3 台账固化）
- 行级 product_category 折算锚点（#14）；回款 settlement_status 预置为 M3 防重锚点
- 评级等级种子四条（迁移+init-dev 双写）；编号前缀常量 YW/SH/HK
- 双轨 SQL 同步（V4/V5 重导，schema_sync+test_models 164 例全绿）

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

backend/app/models/__init__.py

@@ -10,6 +10,7 @@
 """
 
 from app.models.base import Base, TimestampMixin
+from app.models.business import Business, BusinessItem, BusinessStatusLog
 from app.models.business_role import BusinessRole
 from app.models.customer import Customer, OwnershipChangeLog
 from app.models.login_log import LoginLog
@@ -17,13 +18,20 @@ from app.models.operation_log import OperationLog
 from app.models.param import ParamChangeBatch, ParamDefinition, ParamValue
 from app.models.personnel import Personnel, PersonnelPlan, PersonnelRegion
 from app.models.product import Product
+from app.models.rating import CustomerRatingGrade
+from app.models.receipt import Receipt
 from app.models.role import Permission, Role, RolePermission
+from app.models.shipment import Shipment, ShipmentItem
 from app.models.user import User, UserRole
 
 __all__ = [
     "Base",
+    "Business",
+    "BusinessItem",
     "BusinessRole",
+    "BusinessStatusLog",
     "Customer",
+    "CustomerRatingGrade",
     "LoginLog",
     "OperationLog",
     "OwnershipChangeLog",
@@ -35,8 +43,11 @@ __all__ = [
     "PersonnelPlan",
     "PersonnelRegion",
     "Product",
+    "Receipt",
     "Role",
     "RolePermission",
+    "Shipment",
+    "ShipmentItem",
     "TimestampMixin",
     "User",
     "UserRole",