Add Stripe payment intents support and product subscription flag

Introduced functionality for handling Stripe payment intents, including creation, retrieval, and cancellation. Added a subscription_allowed flag to products for enabling subscription-specific operations. Integrated the necessary backend endpoints, object property updates, and route handling logic.

services/nginx/app/routes/productsRoute.php

@@ -22,6 +22,7 @@ class productsRoute
                     'name' => (string)$product['name'],
                     'description' => (string)$product['description'],
                     'price' => (int)$product['price'],
+                    'subscription_allowed' => (boolean)$product['subscription_allowed'],
                     'category' => (int)$product['category'],
                     'piktogram' => (string)$product['piktogram'],
                     'economic_product_id' => (int)$product['economic_product_id'],
@@ -174,6 +175,9 @@ class productsRoute
                 if (self::isParametersSet(['price'])) {
                     $product->price->set($response->getRequestParameter('price'));
                 }
+                if (self::isParametersSet(['subscription_allowed'])) {
+                    $product->subscription_allowed->set($response->getRequestParameter('subscription_allowed') ? 1 : 0);
+                }
                 if (self::isParametersSet(['category'])) {
                     $product->category->set($response->getRequestParameter('category') ?? '');
                 }