Creates a new merchant account on PayU. Returns mid and uuid identifiers used in all subsequent steps.
Step 00 (Authentication) — valid bearer token required
All entities — this is always the first onboarding step.
📘Only display_name, email, and mobile are sent here- Do NOT send business_entity_type in this step — it is set in Step 02- email must be unique across PayU — duplicate emails are rejected- Store both mid and uuid from the response — different APIs require different identifiers
