ver. 0.294: Remove all 12 legacy autoload/shop/ classes (~2363 lines)

Complete Domain-Driven Architecture migration:
- Phase 1-4: Transport, ProductSet, Coupon, Shop, Search, Basket,
  ProductCustomField, Category, ProductAttribute, Promotion
- Phase 5: Order (~562 lines) + Product (~952 lines)
- ~20 Product methods migrated to ProductRepository
- Apilo sync migrated to OrderAdminService
- Production hotfixes: stale Redis cache (prices 0.00), unqualified
  Product:: refs in LayoutEngine, object->array template conversion
- AttributeRepository::getAttributeValueById() Redis cache added

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

templates/shop-basket/_partials/product-custom-fields.php

@@ -1,6 +1,6 @@
 <? if ( $this -> custom_fields ) : ?>
   <? foreach ( $this -> custom_fields as $key => $val ) : ?>
-    <? $custom_field = \shop\ProductCustomField::getFromCache( $key ); ?>
+    <? $custom_field = ( new \Domain\Product\ProductRepository( $GLOBALS['mdb'] ) )->findCustomFieldCached( $key ); ?>
     
     <? if ( $custom_field['type'] == 'text' ) : ?>
       <div class="custom-field">