ver. 0.319: usunięcie shopPRO eksportu produktów + rozszerzenie API o custom_fields i security_information

- Usunięto shopproExportProduct() z IntegrationsRepository
- Usunięto shoppro_product_export() z IntegrationsController
- Usunięto przycisk "Eksportuj do shopPRO" z ShopProductController
- ProductRepository: dodano custom_fields i security_information do odpowiedzi API
- Zaktualizowano docs/API.md i testy

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

autoload/Domain/Product/ProductRepository.php

@@ -682,6 +682,7 @@ class ProductRepository
                     'tab_name_2' => $lang['tab_name_2'],
                     'tab_description_2' => $lang['tab_description_2'],
                     'canonical' => $lang['canonical'],
+                    'security_information' => $lang['security_information'] ?? null,
                 ];
             }
         }
@@ -733,6 +734,10 @@ class ProductRepository
             }
         }
 
+        // Custom fields (Dodatkowe pola)
+        $customFields = $this->db->select('pp_shop_products_custom_fields', ['name', 'type', 'is_required'], ['id_product' => $id]);
+        $result['custom_fields'] = is_array($customFields) ? $customFields : [];
+
         // Variants (only for parent products)
         if (empty($product['parent_id'])) {
             $result['variants'] = $this->findVariantsForApi($id);