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>

tests/Unit/admin/Controllers/IntegrationsControllerTest.php

@@ -118,7 +118,6 @@ class IntegrationsControllerTest extends TestCase
             'shoppro_settings',
             'shoppro_settings_save',
             'shoppro_product_import',
-            'shoppro_product_export',
         ];
 
         foreach ($methods as $method) {
@@ -158,7 +157,6 @@ class IntegrationsControllerTest extends TestCase
             'apilo_product_select_delete',
             'shoppro_settings_save',
             'shoppro_product_import',
-            'shoppro_product_export',
         ];
 
         foreach ($voidMethods as $method) {