webportnoy/telegram_bot ? reverse-engineered prompt

Build me a simple Telegram bot starter in PHP that I can copy onto my site and run without any extra dependencies. I want a basic setup page where I can paste my bot token from BotFather, then a working example bot that responds to a few commands like start, help, and a custom hello message.

Please include support for Telegram features like sending messages, editing and deleting messages, inline keyboards, and callback handling when someone taps a button. It would be great if it also works with group and channel chats, and can use an HTTP proxy if needed.

Keep it easy to customize so I can add my own commands and responses in one place. If any current Telegram API details have changed, look up the latest docs online and make sure the example still works. I mainly want a clean, simple, working starter I can upload, configure, and test right away.