Protocols: Clash: fix Clash app_name not found

app/Http/Controllers/Client/Protocols/Clash.php

@@ -20,6 +20,7 @@ class Clash
     {
         $servers = $this->servers;
         $user = $this->user;
+        $app_name = config('v2board.app_name', 'V2Board');
         header("subscription-userinfo: upload={$user['u']}; download={$user['d']}; total={$user['transfer_enable']}; expire={$user['expired_at']}");
         header('profile-update-interval: 24');
         header("content-disposition: filename={$app_name}");