podman(): container left Exited after SIGINT under load (rm -f killed by its 5 s timeout) #1363

Found by the weekly verify on 2026-11-01, on main@0460513 (reverify-local-sandboxes). It's the same symptom as #1084, which was closed after #1097.

What happens

Under machine load, a SIGINT during a podman() run can leave the container killed but never removed: it sits at Exited (137) until manual cleanup. This happened in 1 of 4 runs at load 13–18. Podman events show the kill 0.38 s after SIGINT, then no remove event. The teardown runs execFileSync("podman", ["rm", "-f", "--time", "0", …]) with a 5 s timeout (src/sandboxes/podman.ts:291-300). The hook's exec session took about 20 s to shut down, so the timeout killed rm and the process exited. Docker's teardown (src/sandboxes/docker.ts:236-244) has no such timeout.

Acceptance

• After a SIGINT, the podman container is removed even when podman rm takes longer than 5 s, or teardown falls back to a detached removal that outlives the process.
• A test or verify claim covers slow removal.

This issue was AI-generated (Claude Code) on behalf of @mattpocock.