[REQUEST] Integration: Telegram user bot (MTProto)

Is your feature request related to a problem? Please describe. Sim’s Telegram integration is Bot API only. There’s no way to use the user API (MTProto) from workflows — e.g. send/receive as a user, use full chats/channels/media. People who need user-bot behaviour have to use workarounds (e.g. HTTP blocks to third‑party services) instead of a native Sim block.

Describe the solution you'd like Add an integration for a Telegram user bot (MTProto) so workflows can call the user API. Auth via my.telegram.org: users create an app and configure their own API ID and API hash (no shared/hardcoded credentials). Store API ID / API hash in env or integration settings.

Describe alternatives you've considered Using only the Bot API: doesn’t cover user-side actions (e.g. read DMs, act as user). Calling external user-bot APIs via HTTP blocks: possible but no native block, no unified credentials, more glue code.

Additional context API methods: https://core.telegram.org/methods TL schema: https://core.telegram.org/schema/mtproto MTProto: https://core.telegram.org/mtproto