How can I place “Add to Watchlist” link to product archive page for all auctions?

You can add this code (thx Mike) to your child theme functions.php file:

// display "add to watchlist" on all product archive pages

add_action( 'woocommerce_shop_loop_item_title', 'add_to_watchlist', 50 );

function add_to_watchlist() {
    global $product;
    if (isset($product) && $product == true) {
        wc_get_template('single-product/watchlist-link.php');
    }
}