Feat(商品):1、库存为0时，加入购物车及立即购买变成灰色；2、库存为0时，相应规格右上角显示缺货标签，并且该缺货规格为灰色不可点击状态

assets/css/style.less

@@ -646,6 +646,7 @@ page {
 }
 
 .product-window .productWinList .item .listn .itemn {
+  position: relative;
   border: 1px solid #bbb;
   font-size: 0.26*100rpx;
   color: #282828;
@@ -659,6 +660,23 @@ page {
   background-color: #eb3729;
   border-color: #eb3729;
 }
+.product-window .productWinList .item .listn .itemn.disabled {
+  color: #333;
+  background-color: #F1F1F1;
+  border-color: #F1F1F1;
+}
+.product-window .productWinList .item .listn .itemn.disabled .tag {
+  position: absolute;
+  top: -18upx;
+  right: -18upx;
+  height: 28upx;
+  padding: 0 6upx;
+  border-radius: 6upx;
+  color: #fff;
+  line-height: 28upx;
+  font-size: 10px;
+  background-color: #FD5749;
+}
 
 .product-window .cart {
   margin-top: 0.36*100rpx;