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/factory/class.ShopProduct.php

@@ -65,19 +65,6 @@ class ShopProduct
     return $mdb -> get( 'pp_shop_products_langs', 'name', [ 'AND' => [ 'product_id' => $product_id, 'lang_id' => $default_lang ] ] );
   }
 
-  // lista produktów do wiązania z baselinkerem
-  static public function products_list_for_baselinker()
-  {
-    global $mdb;
-
-    $results = $mdb -> select( 'pp_shop_products', [ 'id', 'sku', 'baselinker_product_id' ], [ 'parent_id' => null, 'ORDER' => [ 'baselinker_product_id' => 'ASC', 'sku' => 'ASC' ] ] );
-    foreach ( $results as $row ) {
-      $row['name'] = self::product_default_name( $row['id'] );
-      $products[] = $row;
-    }
-    return $products;
-  }
-
   // szybka zmiana google xml label
   static public function product_change_custom_label( int $product_id, $custom_label, $value )
   {