Collection attempt reversed

Webhook event triggered when a previously successful payment attempt against a collection is reversed (the underlying incoming transfer was reversed by Bre-B reconciliation).

The reversed amount is subtracted from the collection's paid_amount, successful_attempts is decremented, and the collection state is recalculated from the remaining paid_amount: a paid or minimum_paid collection may reopen as ready or minimum_paid. The attempt transitions to reversed with state_reason: transfer_reversed.