Add ManagesSocialiteUsers concern and resources for listing third-party connections

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

src/Id/Resources/SocialiteUsers.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Anikeen\Id\Resources;
+
+use Anikeen\Id\Concerns\HasParent;
+
+class SocialiteUsers extends BaseCollection
+{
+    use HasParent;
+
+    public function find(string $id): ?SocialiteUser
+    {
+        return null;
+    }
+}