ver. 0.302: REST API product variants, attributes dictionary, attribute filtering

- Add variant CRUD endpoints (variants, create_variant, update_variant, delete_variant)
- Add dictionaries/attributes endpoint with multilingual names and values
- Add attribute_* filter params for product list filtering by attribute values
- Enrich product detail attributes with translated names (attribute_names, value_names)
- Include variants array in product detail response for parent products
- Add price_brutto validation on product create
- Batch-load attribute/value translations (4 queries instead of N+1)
- Add 43 new unit tests (730 total, 2066 assertions)

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

autoload/api/Controllers/DictionariesApiController.php

@@ -2,6 +2,7 @@
 namespace api\Controllers;
 
 use api\ApiRouter;
+use Domain\Attribute\AttributeRepository;
 use Domain\ShopStatus\ShopStatusRepository;
 use Domain\Transport\TransportRepository;
 use Domain\PaymentMethod\PaymentMethodRepository;
@@ -11,15 +12,18 @@ class DictionariesApiController
     private $statusRepo;
     private $transportRepo;
     private $paymentRepo;
+    private $attrRepo;
 
     public function __construct(
         ShopStatusRepository $statusRepo,
         TransportRepository $transportRepo,
-        PaymentMethodRepository $paymentRepo
+        PaymentMethodRepository $paymentRepo,
+        AttributeRepository $attrRepo
     ) {
         $this->statusRepo = $statusRepo;
         $this->transportRepo = $transportRepo;
         $this->paymentRepo = $paymentRepo;
+        $this->attrRepo = $attrRepo;
     }
 
     public function statuses(): void
@@ -79,4 +83,15 @@ class DictionariesApiController
 
         ApiRouter::sendSuccess($result);
     }
+
+    public function attributes(): void
+    {
+        if (!ApiRouter::requireMethod('GET')) {
+            return;
+        }
+
+        $attributes = $this->attrRepo->listForApi();
+
+        ApiRouter::sendSuccess($attributes);
+    }
 }