feat(business): 业务管理接口（编号生成/明细/状态机/归属留痕/毛利润视图）

- 编号 YW{日期}-{序号}：MAX+FOR UPDATE 并发安全 + 1062 兜底重试（no_generator 三单据共用）
- 明细全量替换重算五项汇总冗余；销售额服务层按数量×单价固化不信任前端
- 状态机终态拦截、终止必填原因、创建写首条留痕；归属变更同事务留痕防旁路
- 毛利润视图按行实时计算（不含运费 #2），阈值按 asOf 取 M1 快照，率输出
  Fraction 分数字符串同 M1 预览口径；成本缺失行标注无法计算
- 入参契约统一为蛇形直出（撤回 customer/business 的驼峰 alias，与前端
  businessRoles.ts 模式对齐）

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

backend/app/api/router.py

@@ -11,6 +11,8 @@ from app.api.v1 import auth
 from app.api.v1.base import customers as base_customers
 from app.api.v1.base import personnel as base_personnel
 from app.api.v1.base import products as base_products
+from app.api.v1.business import businesses as business_businesses
+from app.api.v1.business import ratings as business_ratings
 from app.api.v1.system import business_roles as system_business_roles
 from app.api.v1.system import logs as system_logs
 from app.api.v1.system import params as system_params
@@ -43,4 +45,10 @@ base_router.include_router(base_products.router)
 base_router.include_router(base_customers.router)
 v1_router.include_router(base_router)
 
+# 业务数据（需求 2.2）：/api/v1/business/*，业务操作登录即可访问
+business_router = APIRouter(prefix="/business")
+business_router.include_router(business_businesses.router)
+business_router.include_router(business_ratings.router)
+v1_router.include_router(business_router)
+
 api_router.include_router(v1_router)