mask deSEC password behind details reveal; add hex length comment

Agent-Logs-Url: https://github.com/nextcloud/all-in-one/sessions/4e99bcbc-4f32-45e6-af08-5026ce4b1f45

Co-authored-by: szaimen <42591237+szaimen@users.noreply.github.com>

php/src/Controller/DesecController.php

@@ -64,6 +64,7 @@ readonly class DesecController {
             if (!$accountAlreadyRegistered) {
                 // Register an account at deSEC and obtain an API token.
                 // The password is stored so the user can log in to desec.io directly if needed.
+                // 24 random bytes encoded as hex produce a 48-character password.
                 $password = bin2hex(random_bytes(24));
                 $token = $this->registerDesecAccount($email, $password);