refactor: event handling

ajax/frontend/shipping.php

@@ -14,7 +14,7 @@ function ($orderHash) {
         $Checkout = new QUI\ERP\Order\SimpleCheckout\Checkout([
             'orderHash' => $orderHash
         ]);
-        
+
         return $Checkout->getShipping();
     },
     ['orderHash']

src/QUI/ERP/Order/SimpleCheckout/CheckoutStepInterface.php

@@ -2,8 +2,19 @@
 
 namespace QUI\ERP\Order\SimpleCheckout;
 
-
+/**
+ * Interface CheckoutStepInterface
+ *
+ * This interface represents a checkout step in a checkout process.
+ * It defines the method that any checkout step must implement.
+ */
 interface CheckoutStepInterface
 {
+    /**
+     * Constructor for the class.
+     *
+     * @param Checkout $Checkout An instance of the Checkout class.
+     * @param array $attributes [optional] An array of attributes (default: empty array).
+     */
     public function __construct(Checkout $Checkout, $attributes = []);
-}
\ No newline at end of file
+}