green-api/whatsapp-api-client-php ? reverse-engineered prompt

Build me a simple PHP app that uses the Green API WhatsApp client library to send and receive WhatsApp messages.

I want a clean starter project that shows how to connect with an instance ID and token from environment variables, send a text message, send an image from a URL or from local files, show a typing indicator, create a group and send a message to it, and listen for incoming webhook notifications. Please include a few working example pages or scripts so I can test each feature quickly, and make the setup easy to run locally with Composer and a built in PHP server.

Keep it simple and practical, with clear sample code and sensible defaults. If you need to check the latest API details online, go ahead and look them up.