Unpublish Course
B2B Courses
Unpublish Course
Remove a course from the owning account's org catalog.
Sets catalog_listed_at=NULL on the caller's OWN course. Idempotent: an
already-unlisted course unpublishes to the same NULL state (no error). 404
"Course not found" if the course_id does not exist or is not owned by the
caller. verified_at is left untouched (admin-only field; unpublish does
not un-verify -- republishing later restores catalog visibility without
re-verification).
Returns 200 {id, catalog_listed_at: null}.