Issue a QR code for signing a Telegram account in

Connecting a Telegram ACCOUNT (not a bot) takes two things a person has to do: type api_id/api_hash/phone into a link form, and then approve a sign-in from a phone that is already logged into Telegram. This endpoint produces the second one.

The response carries the same login token twice: qr_svg is ready-to-embed SVG markup, login_url is the tg://login?token=… link encoded inside that image. Show whichever your surface can actually render — on a phone the link opens the Telegram confirmation directly, with nothing to scan.

NOT idempotent, and this is the important part: every call mints a NEW login token and kills the previous one. Do not call it on a timer. Call it once, then poll GET /api/v1/credentials/telegram/qr and call this again ONLY when that poll answers expired.

Requires api_id, api_hash and phone to be stored already — ask for them with POST /api/v1/credentials/telegram/request first, otherwise this answers 422 saying what is missing.

Two different situations answer 200 with no token, and they are NOT the same: already_authorized means the account is connected and there is nothing left to do, while 2fa_required means an earlier scan already succeeded and the session is waiting for the two-step password. On 2fa_required do not issue again and do not report the channel as connected — ask for a password link with POST /api/v1/credentials/telegram_2fa/request and poll GET /api/v1/credentials/telegram/qr until it reads authorized.