* test(e2e): close Podman driver test coverage gaps
Add podman_gateway_resume test following the VM pattern (no
container-state assertions since Podman keeps containers running across
gateway restarts). Widen websocket_conformance feature gate from
e2e-docker to e2e-host-gateway so it runs on both Docker and Podman.
Fix e2e-podman.sh to default to the e2e-podman feature so Podman-
specific and host-gateway tests are actually included in Podman CI runs.
* refactor(e2e): extract shared CLI helpers from gateway_resume tests
Move run_cli, wait_for_healthy, sandbox_names, and
wait_for_sandbox_exec_contains into a new harness::cli module. All three
gateway_resume variants (Docker, Podman, VM) now import these shared
helpers instead of defining identical copies. Docker-specific container
introspection functions remain local to gateway_resume.rs.
Russell Bryant