批次5：inventory服务下沉收口 + Pydantic v2 / datetime弃用清零

- inventory业务层下沉（薄路由+service orchestration模式）：
  - customer/supplier/warehouse -> master_data_service
  - material_routes（价格历史/趋势/供应商关联）-> material_service
  - product_routes（CRUD/BOM/from-task跨模块桥接）-> product_service
  - dashboard_routes（首页统计/低库存预警）-> dashboard_service
- inventory侧新增service回归覆盖（dashboard 2 / master_data 10 /
  material 10 / product 14），含跨模块桥接测试种子
- Pydantic v2弃用清零：全仓14处 class Config 全部迁移到
  model_config = ConfigDict(from_attributes=True)（含 shared auth）
- datetime.utcnow() 弃用清零：auth_service 3处统一改 datetime.now(timezone.utc)
- 同步文档：STATUS / ROADMAP / TECH_DEBT（D12清偿）/ AGENTS 代码地图

测试基线：126 passed, 4 skipped（无deprecation warning）

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

src/inventory/schemas/__init__.py

@@ -54,7 +54,8 @@ from .material_schemas import (
     MaterialPriceHistoryResponse,
     MaterialSupplierCreate,
     MaterialSupplierResponse,
-    MaterialPriceTrendResponse
+    MaterialPriceTrendResponse,
+    PriceHistoryItem
 )
 from .purchase_demand_schemas import (
     PurchaseDemandCalculateRequest,
@@ -89,6 +90,6 @@ __all__ = [
     "PartnerStatementItemResponse", "FinancePartnerStatementResponse",
     "PartnerProductStatementItemResponse", "FinancePartnerProductStatementResponse",
     "MaterialPriceHistoryCreate", "MaterialPriceHistoryResponse",
-    "MaterialSupplierCreate", "MaterialSupplierResponse", "MaterialPriceTrendResponse",
+    "MaterialSupplierCreate", "MaterialSupplierResponse", "MaterialPriceTrendResponse", "PriceHistoryItem",
     "PurchaseDemandCalculateRequest", "PurchaseDemandItemResponse", "PurchaseDemandResponse",
 ]