Initiate a payout reversal

This POST endpoint is used to initiate a reversal of a previously completed payout transaction.
You must specify the user_token and original payout (payout_token) in the URL path to identify which transaction should be reversed.
In the request body, you may optionally provide an amount to perform a partial reversal. If no amount is specified, the entire payout amount will be reversed.
Reversals can be performed multiple times until the full payout has been reversed.
Once the payout has been fully reversed, additional reversal attempts will be rejected. Attempting to reverse more than the remaining available amount will also result in an error.
The response will include the details of the reversal transaction, including the amount reversed, the remaining reversible balance (if any), and the status of the original payout.