Request contract activation OTP
Begin contract activation by requesting an OTP. The system first compares the user's current location against their last active device location.
- **Within 80 km:** OTP is sent. Save the returned `otpRequestId` for `StepValidateOtp`.
- **More than 80 km:** The response indicates that liveness re-validation is required. Call `StepReValidateLiveness` first, then retry this endpoint.

