A ExGram.BotInit hook that calls ExGram.get_me/1 at bot startup to populate bot_info with the bot's User struct.

This hook is automatically injected by the dispatcher when get_me: true (which is the default). Disable it with get_me: false when starting the bot:

{MyBot, [method: :polling, token: token, get_me: false]}

In tests, ExGram.Test.start_bot/3 defaults to get_me: false to avoid making API calls.

On success the hook returns {:ok, %{bot_info: user}}. The dispatcher extracts bot_info from extra_info after all hooks have run and stores it on the dispatcher state, so it never leaks into Cnt.extra.