Add api scope enum

src/Enums/Scope.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace GhostZero\BitinflowAccounts\Enums;
+
+/**
+ * @author René Preuß <rene@preuss.io>
+ */
+class Scope
+{
+
+    /*
+     * v0 API
+     */
+
+    // Deprecated scope.
+    const API = 'api';
+
+    // Read nonpublic user information, including email address.
+    const READ_USER = 'read_user';
+}