Telegram

Make authentication work with:

1. Websites that receive a signed payload from a "seamless login" link
2. Mini-Apps that received a signed payload from Telegram app
3. The "message" update in a private chat with a bot's "/start" command
4. When a bot receives a service message

In addition, there can be three other messages:
5. The "message" update in a public chat the bot is in
6. A "pinned_message" in a public chat the bot is in
7. A "new_chat_members" update in a chat the bot is in
8. A "users_shared" update, when users are shared with the bot

In cases 5-8, please create a futureUser instead. There should be an option to import the username and download the image, even for a futureUser. When the user finally uses 1-4 to authenticate, this futureUser would be "adopted".