Two probe test-infra fixes needed to validate the keep-alive hardening (b53710d) on glass:
- `--seconds N` caps the receive loop (was a hardcoded 120s), so a probe against a live `serve`
host ends its session promptly and reaches the graceful `conn.close`.
- After `conn.close`, wait for the endpoint to flush the CONNECTION_CLOSE frame (bounded 2s)
before exiting — otherwise the process drops the endpoint before quinn sends the close, and the
host waits out the idle timeout instead of seeing the close CODE (which the `--quit` deliberate-
quit path and normal code-0 close both depend on).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
b71dc94bb2