add set layout api

backend/app/Set/UseCases/GetSetLayout/SetLayout.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace App\Set\UseCases\GetSetLayout;
+
+use App\Set\Set;
+
+final readonly class SetLayout
+{
+    /**
+     * @param list<ElementLayoutNode> $elements
+     */
+    public function __construct(
+        private Set $set,
+        private array $elements,
+    ) {}
+
+    public function getSet(): Set
+    {
+        return $this->set;
+    }
+
+    /**
+     * @return list<ElementLayoutNode>
+     */
+    public function getElements(): array
+    {
+        return $this->elements;
+    }
+}