Onchain sendAll payments are not accounting for fees #270
Description
The OnChainPaymentSendAll mutation is failing because we're sending Ibex the entire wallet balance.
The best fix to this issue would be to have Ibex add a sendAll flag. I created another feature request with them: https://flash-qwj9494.slack.com/archives/C04K5NC9D3N/p1770220431805969
If they cannot support this, we should fetch the estimated fee and subtract from the wallet balance to get the proper amount. Note, if this fee differs from the fee used by Ibex, this may either fail or not sweep the entire balance.