Custom post type – how to name file?

If I understood correctly, all you have to do is add 'publicly_queryable' => FALSE, to your arguments array.

And the individual archive template file would be archive-kalendar_radova.php, that’s right.

// Edit
In order to have a single view of your CPT be redirected to the according archive, put the following to your functions.php file:

function wpdev_169737_redirect_single_cpt_to_archive() {

    $post_type="your-cpt-here";
    if ( is_singular( $post_type ) ) {
        wp_safe_redirect( get_post_type_archive_link( $post_type ) );
        exit();
    }
}

add_action( 'template_redirect', 'wpdev_169737_redirect_single_cpt_to_archive' );