refactor(phpstan): change order interface to erp entity interface in Discount

Updated the 'canUsedInOrder' function in Discount.php to accept ERP Entity Interface arguments
instead of Order Interfaces for better flexibility and compatibility. Added checks to ensure that
the provided entity is an instance of the Order Interface, increasing robustness.

src/QUI/ERP/Discount/Discount.php

@@ -437,15 +437,23 @@ public function canUsedWith(QUI\ERP\Products\Interfaces\ProductInterface $Produc
     }
 
     /**
-     * @param OrderInterface $Order
+     * @param QUI\ERP\ErpEntityInterface $Order
      * @return bool
      */
-    public function canUsedInOrder(OrderInterface $Order): bool
+    public function canUsedInOrder(QUI\ERP\ErpEntityInterface $Order): bool
     {
         if ($this->isActive() === false) {
             return false;
         }
 
+        if (!interface_exists('QUI\ERP\Order\OrderInterface')) {
+            return false;
+        }
+
+        if (!($Order instanceof QUI\ERP\Order\OrderInterface)) {
+            return false;
+        }
+
         $Articles = $Order->getArticles();
 
         foreach ($Articles as $Article) {