Bare `/tapir` runs the long-running server, same as the old ctr-based smoke test. ctr's --rm reliably force-killed it; a plain `timeout N buildah run` does not — it only signals the wrapper, and the container process can survive that and keep the log pipe open, hanging the whole job (observed live: run 155, 14min before failure). Backgrounds the run and tears it down with `buildah rm -f`, which forcibly kills regardless of wrapper state, and captures output via a file instead of a blocking pipe. Refs infra#132.