Fixes: 1) Correct `serializer_class` assignments for `ProductImageViewSet`, `PromoCodeViewSet`, `PromotionViewSet`, `StockViewSet`, and `WishlistViewSet`.
Extra: 1) General code cleanup and reorganization for viewsets.
Enhanced the `deepl_translate` management command with improved placeholder handling, error messages, and support for missing translations. Added `human_readable_id` and `is_business` attributes to the `Order` model, updating associated admin configurations to reflect these changes.