Update the outcome for a job that has already had its outcome reported — for example correcting a status that an SDK reported wrongly. Requires reason (why the record is being changed); the update is recorded in the outcome history. outcomeReason (why the job itself failed) is separate and optional: omit it to keep the current value, send an empty string to clear it. Returns 422 if no outcome has been reported yet, or if reason is missing or blank. Returns 409 if a concurrent update conflict is detected.