fix(email): lock templates to built-in catalog

src/Settings/MailNotifications.php

@@ -192,7 +192,7 @@ final class MailNotifications {
     private static function send(string $event, string $to, array $vars): void {
         $placeholders = [];
         foreach ($vars as $key => $value) $placeholders['{' . $key . '}'] = (string) $value;
-        Mail::send_event_email($event, $to, '', '', $placeholders);
+        Mail::send_event_email($event, $to, $placeholders);
     }
 
     /** @param array<string,mixed> $vars */