Integrations DI refactor, remove Sellasist/Baselinker, fix product-edit encoding (0.263)

- New: Domain\Integrations\IntegrationsRepository + admin\Controllers\IntegrationsController (DI)
- Cleanup: removed all Sellasist and Baselinker integrations from entire project
- Fix: product-edit.php Polish characters (UTF-8/CP1250 double-encoding)
- Update: factory\Integrations as facade (Apilo + ShopPRO only)
- Tests: 212 tests, 577 assertions

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

autoload/admin/controls/class.ShopProduct.php

@@ -297,9 +297,7 @@ class ShopProduct
         'html' => \Tpl::view( 'shop-product/products-list-table', [
           'products' => $products['products'],
           'current_page' => \S::get( 'current_page' ),
-          'baselinker_enabled' => \admin\factory\Integrations::baselinker_settings( 'enabled' ),
           'apilo_enabled' => \admin\factory\Integrations::apilo_settings( 'enabled' ),
-          'sellasist_enabled' => \admin\factory\Integrations::sellasist_settings( 'enabled' ),
           'show_xml_data' => \S::get_session( 'show_xml_data' )
         ] )
       ];
@@ -334,9 +332,7 @@ class ShopProduct
       'current_page' => $current_page,
       'query_array' => $query_array,
       'pagination_max' => ceil( \admin\factory\ShopProduct::count_product() / 10 ),
-      'baselinker_enabled' => \admin\factory\Integrations::baselinker_settings( 'enabled' ),
       'apilo_enabled' => \admin\factory\Integrations::apilo_settings( 'enabled' ),
-      'sellasist_enabled' => \admin\factory\Integrations::sellasist_settings( 'enabled' ),
       'show_xml_data' => \S::get_session( 'show_xml_data' ),
       'shoppro_enabled' => \admin\factory\Integrations::shoppro_settings( 'enabled' )
     ] );