Mutation - reverseAccountingAllocationRun

Reverses a posted run: writes the reversing journal against the run's own posted entry, closes that entry, and stamps the run reversed — all in one transaction. This is the only way to undo a posted allocation; reverseJournal refuses the run's journal because it is owned by a document lifecycle, which is this one. Access: signed-in members of the run's workspace with the accountingUnpost permission, in a workspace where finance is enabled. Errors: run not found; the run is not posted; its journal is missing; the reason is empty once markup is stripped; the reversal date falls before the original posting date or in a closed period; or the run changed while it was being reversed.