fix: Fail-Closed 字段级安全加固 — 堵住15+端点价格泄露

## stock.py
- _make_price_stripper(): 工厂函数,选单前缀自动剥离所有价格/成本字段
- _do_get_stock_list(permission_prefix): 每个item.to_dict()后剥离价格
- /all 端点: 非AI模式自动剥离价格字段
- /list 端点: permission_prefix='outbound_selection' 传递

## outbound.py
- /bom-match-stock: 返回前按stock_type剥离全部价格/成本字段
- /scan: result.pop('price', None)

## scrap.py
- /scan: result.pop('price', None)
- /records: 每条记录剥离 cost_at_scrap, total_loss

## transactions.py
- filter_item_by_permissions: 从空字典恢复完整20字段映射
- /borrow/stock-list: permission_prefix='op_borrow_apply' 传递

## buy.py / semi.py / product.py
- submit 成功响应剥离所有价格/成本字段(不泄露给前端)

## bom.py
- /base/list: 剥离 referencePrice

inventory-backend/app/api/v1/inbound/buy.py

@@ -252,10 +252,16 @@ def submit():
 
         new_stock = BuyInboundService.handle_inbound(data)
 
+        # ★ Fail-Closed: 入库成功响应剥离价格字段
+        resp = new_stock.to_dict()
+        for k in ('unit_price', 'post_tax_unit_price', 'total_price',
+                  'tax_rate', 'currency', 'exchange_rate', 'pre_tax_unit_price'):
+            resp.pop(k, None)
+
         return jsonify({
             "code": 200,
             "msg": "入库成功",
-            "data": new_stock.to_dict()
+            "data": resp
         })
     except Exception as e:
         traceback.print_exc()