Create RFQ

Creates an RFQ for the authenticated account. RFQ creation is asynchronous. Subscribe to the private WebSocket channel `rfq` before sending the request. A successful HTTP response is `202 Accepted` and contains a Paradex `request_id`; it confirms only that the command was queued. The later WebSocket `RESULT` event with the same `request_id` reports whether the venue accepted the command. On success, the event's top-level `rfq_id` is the venue-issued identifier used by the read, execute, cancel, and filtered-subscription APIs. The request accepts up to 25 legs. It must contain at least one strategy leg, represented by omitting `price`. At least one strategy leg must have `side=BUY`, and at least one must have `ratio=1`. A fixed-price hedge leg includes a strictly positive `price`. All quantities and ratios are positive decimal strings. Every leg market must exist on Paradex and be available for RFQ. Each fixed hedge price must be an exact multiple of that market's minimum price increment. The strategy quantity must be at least the largest minimum block size among its strategy legs. The platform selects eligible counterparties; a client-supplied `counterparties` value is ignored. The optional `strategy` field is a draft label and is not sent to the venue. Validation or risk-check failures that occur after queueing are reported by the WebSocket `RESULT` event.