List MED disputes (Special Return Mechanism)

Lists the disputes filed against this account, newest first. The data is ours: the settlement bank exposes no lookup and no listing for infraction reports, so this endpoint reads what the `pix.med.opened` / `pix.med.updated` webhooks recorded. Subscribing to those webhooks is therefore part of integrating MED — see the Disputes guide. There is no dispute status here, and no filter by it. Without a lookup at the settlement bank the stored state cannot be confirmed, so the endpoint exposes what is verifiable instead: whether you answered (`answered`) and your deadline (`clientAnswerDeadline`). To track state, accumulate the `pix.med.updated` events — their `status` is accurate for the instant of the event.