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/objects/departments_o.php

@@ -305,4 +305,19 @@ class departments_o extends db
         }
         return $tmp;
     }
+
+    /**
+     * Check if the Stripe is configured for the department
+     * @note This is a link to the department_variables_o::isSet(stripe_terminal_location) method
+     * @return bool true If the Stripe is configured
+     * @throws Exception If the department is not selected
+     */
+    public function isStripeConfigured(): bool
+    {
+        self::requireSelected();
+        if ($this->variables->isSet('stripe_terminal_location')) {
+            return true;
+        }
+        return false;
+    }
 }