Full acceptance test: admin auth (+ student-can't-call-admin check),
cohort create, 3-student add, curriculum assign, concurrent Prepare Labs
(3/3 ready, instant-reuse timing check), two students completing
different scenarios, dashboard reflecting completions, admin reset with
progress-intact assertion, admin destroy-labs with progress-intact
assertion for everyone, and a regression check that no Lab container
publishes a host port. 12/12 passing.
