better-route: install and migrate to 1.1

Install

Require the stable 1.1 line directly from Packagist:

composer require better-route/better-route:^1.1
composer show better-route/better-route

Use PHP 8.1 or newer. Do not add a VCS repository unless intentionally consuming a fork or unreleased branch.

Register routes during rest_api_init:

use BetterRoute\Router\Router;