Restore an archived course by its Edusign id: its lock is cleared (isArchived: false) and it becomes editable and signable again. This is the explicit v3 counterpart of PATCH /v1/course/unlock/:courseId.

⚠️ Only the course’s own lock is cleared. Its parent training is not touched: a course can be restored while its training stays archived. The operation is not retroactive either: a signature-collection email skipped while the course was locked is not resent; the scheduled reminders of a future course are re-armed.

An unknown id, or one belonging to another school, answers 404 COURSE_NOT_FOUND; a course that is not archived answers 409 COURSE_NOT_ARCHIVED.

Fires the on_course_unarchived webhook ({ courseId }) once per successful restore, asynchronously, next to the legacy on_course_unlocked; a delivery failure never changes this response.