expose sets list endpoint

backend/app/Set/UseCases/ListSets/ListSets.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Set\UseCases\ListSets;
+
+use App\Set\Set;
+use App\Set\SetRepository;
+
+class ListSets
+{
+    public function __construct(
+        private SetRepository $setRepository,
+    ) {}
+
+    /**
+     * @return list<Set>
+     */
+    public function execute(): array
+    {
+        return $this->setRepository->all();
+    }
+}