implement ListFeaturedPosts use case

backend/app/Post/UseCases/ListFeaturedPosts/ListFeaturedPosts.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Post\UseCases\ListFeaturedPosts;
+
+use App\Post\Post;
+use App\Post\PostRepository;
+
+class ListFeaturedPosts
+{
+    public function __construct(
+        private PostRepository $postRepo,
+    ) {}
+
+    /**
+     * @return Post[]
+     */
+    public function execute(): array
+    {
+        return $this->postRepo->findFeatured();
+    }
+}