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/admin/Controllers/ShopProductController.php

@@ -140,14 +140,6 @@ class ShopProductController
                 }
             }
 
-            if ( $shopproEnabled ) {
-                $row['_actions'][] = [
-                    'label'   => 'Eksportuj do shopPRO',
-                    'url'     => '/admin/integrations/shoppro_product_export/product_id=' . $id,
-                    'class'   => 'btn btn-xs btn-system',
-                    'confirm' => 'Na pewno chcesz wyeksportowac ten produkt do shopPRO?',
-                ];
-            }
 
             $rows[] = $row;
         }