unblockOutboundStream

Unblock an integration's outbound stream halted by the block poison policy: skips (dead-letters) the current blocked head message, emitting MSG_DEAD_LETTERED and letting the next message become the head. A head blocked because its jsonata_expression failed at enqueue is skipped the same way (its DLQ reason defaults to mapping_failed); fix the expression, then redrive the entry to re-map it. Operator endpoint — requires the integration:manage grant. Returns unblocked: false as a no-op when the stream is not currently blocked (or the state moved concurrently) — safe to retry.