Remapped backend endpoints to /backend instead of /backends.

src/API/System/Supported.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\API\System;
+
+use App\Libs\Attributes\Route\Get;
+use App\Libs\Config;
+use App\Libs\HTTP_STATUS;
+use Psr\Http\Message\ResponseInterface as iResponse;
+use Psr\Http\Message\ServerRequestInterface as iRequest;
+
+final class Supported
+{
+    public const string URL = '%{api.prefix}/system/supported';
+
+    #[Get(self::URL . '[/]', name: 'system.supported')]
+    public function __invoke(iRequest $request): iResponse
+    {
+        return api_response(HTTP_STATUS::HTTP_OK, [
+            'supported' => array_keys(Config::get('supported')),
+        ]);
+    }
+}