Creates an on-chain prediction market from a processed question. The questionId must come from a completed question submission (POST /questions → poll until complete).
This endpoint is idempotent — if a market already exists for the given question, it returns the existing market ID and transaction hash.
API key passed as Bearer token
Question to create a market for
Question ID (hex hash) from a completed question submission
"0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef"