MoMo Voucher Distribution API
API for creating and distributing promotion campaigns and voucher codes to MoMo users, and for reconciling redemption. Create and update campaigns, upload voucher codes by file, query campaign and voucher-code status, and post redemption results back to MoMo. Authenticated with clientId/clientSecret exchanged for a 24-hour bearer access token; every request carries an X-Request-Id UUID.