feat: 出库/借库记录记录并展示库位快照（DB加列+后端写入+记录页展示）

inventory-backend/app/services/outbound_service.py

@@ -278,6 +278,8 @@ class OutboundService:
                     quantity=quantity,
                     unit_price=unit_price,
                     outbound_time=current_time,
+                    # [新增] 记录出库时的库位快照
+                    warehouse_location=getattr(stock_record, 'warehouse_location', None),
                     **common_data
                 )
                 db.session.add(new_record)
@@ -647,7 +649,9 @@ class OutboundService:
                 'quantity': qty,
                 'unit_price': price,
                 'subtotal': subtotal,
-                'batch_sn': batch_sn
+                'batch_sn': batch_sn,
+                # [新增] 出库时的库位快照（展示用）
+                'warehouse_location': getattr(d, 'warehouse_location', None) or ''
             })
 
         # 4. 排序输出