Refunds one prefund escrow's remainder to its owner's spendable balance, by the deterministic
esc_refund_ txn id every repair path shares: the lane's own close, the orphan sweep, and the
retention sweep post this identical entry, so whichever runs first wins and the rest no-op on
the existing posting. Returns the refunded minor amount, or null when the escrow is empty or
already refunded.
Refunds one prefund escrow's remainder to its owner's spendable balance, by the deterministic
esc_refund_txn id every repair path shares: the lane's own close, the orphan sweep, and the retention sweep post this identical entry, so whichever runs first wins and the rest no-op on the existing posting. Returns the refunded minor amount, or null when the escrow is empty or already refunded.