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>

tests/test_api_dashboard_service.py

@@ -0,0 +1,39 @@
+import pytest
+
+
+@pytest.mark.anyio
+async def test_dashboard_returns_seeded_summary(client):
+    resp = await client.get("/api/dashboard")
+    assert resp.status_code == 200
+    body = resp.json()
+    assert body["material_count"] == 1
+    assert body["finished_product_count"] == 2
+    assert body["supplier_count"] == 1
+    assert body["customer_count"] == 1
+    assert body["warehouse_count"] == 1
+    assert body["total_stock"] == 1000
+    assert float(body["total_value"]) == 10000.0
+    assert body["pending_purchase"] == 0
+    assert body["pending_sales"] == 0
+    assert body["low_stock_products"] == []
+
+
+@pytest.mark.anyio
+async def test_dashboard_low_stock_products_are_listed(client):
+    inventory = await client.get("/api/inventory")
+    assert inventory.status_code == 200
+    inv_id = next(row["id"] for row in inventory.json()["items"] if row["product_sku"] == "MAT-001")
+
+    updated = await client.put(
+        f"/api/inventory/{inv_id}",
+        json={"quantity": 0, "locked_quantity": 0},
+    )
+    assert updated.status_code == 200
+
+    resp = await client.get("/api/dashboard")
+    assert resp.status_code == 200
+    low_stock = resp.json()["low_stock_products"]
+    assert len(low_stock) == 1
+    assert low_stock[0]["sku"] == "MAT-001"
+    assert low_stock[0]["quantity"] == 0
+    assert low_stock[0]["min_stock"] == 0