Start the human delegation (approval) flow needed for checkout/payment. PREFERRED: pass the buyer's `email` — the gateway emails them a 6-digit code and returns a device_code; ask the user for the code and call submit_delegation_otp. This keeps approval fully in-chat (no link) and you never see the code, so you cannot approve on their behalf. If you omit `email`, it falls back to a browser approval link (device flow) which the user must open; then poll check_delegation. You can never approve a delegation yourself.
ConnectorNo auth