fix(api): fix AttributeError on inbound deletion by accessing base.name instead of material_name

inventory-backend/app/services/inbound/buy_service.py

@@ -281,8 +281,8 @@ class BuyInboundService:
         try:
             stock = StockBuy.query.get(stock_id)
             if not stock: raise ValueError("记录不存在")
-            # 提前获取物料名称用于审计日志
-            material_name = stock.material_name
+            # 提前获取物料名称用于审计日志（通过外键关系 base.name 获取）
+            material_name = stock.base.name if stock.base else '未知物料'
             db.session.delete(stock)
             db.session.commit()
             return material_name