You got parentheses levels slightly wrong and that broke your callbacks.
It should be:
add_action( 'wp_enqueue_scripts', array( __CLASS__, 'frontend_enqueues' ), 1 );
You got parentheses levels slightly wrong and that broke your callbacks.
It should be:
add_action( 'wp_enqueue_scripts', array( __CLASS__, 'frontend_enqueues' ), 1 );