Register a business as an SME (step-based)

Registers a business as its own SME so that dedicated virtual accounts are issued under the business's own legal entity rather than the shared default. The flow is stateful and driven by this single endpoint: the step field selects the payload carried in data. Call the steps in order: INITIATE (triggers a one-time passcode to the supplied mobile number), CONFIRM_OTP, then SUBMIT (company details, directors and documents). Upload each document first via POST /api/v1/media/url and pass the returned object keys in the SUBMIT payload. Calling INITIATE again while the registration is still waiting for its passcode returns that same registration with a 200. Requires the COMPLIANCE.KYB.SUBMIT key permission.