add sets endpoint

backend/app/Controllers/SetController.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Controllers;
+
+use App\Set\Set as DomainSet;
+use App\Set\SetRepository;
+use Illuminate\Http\JsonResponse;
+
+class SetController
+{
+    public function __construct(private SetRepository $setRepository) {}
+
+    public function index(): JsonResponse
+    {
+        $sets = [];
+        foreach ($this->setRepository->getAll() as $set) {
+            $sets[] = $this->buildSetPayload($set);
+        }
+
+        return new JsonResponse([
+            'sets' => $sets,
+        ], 200);
+    }
+
+    /**
+     * @return array{id: int, name: string}
+     */
+    private function buildSetPayload(DomainSet $set): array
+    {
+        return [
+            'id' => $set->getId(),
+            'name' => $set->getName(),
+        ];
+    }
+}