The changed-tests workflow overrode the suite's `--reruns 1` with `--reruns 0`, so a
transport blip failed a pass that pytest.ini already scopes to network errors and
5xx responses. Pass 2 of run 33692484803 also went red 15s after a model write with
"no healthy deployments": the barrier only polled /v1/models through nginx, which
proves one gateway converged, and the next request rolled the other. The stack now
exports LITELLM_PROXY_REPLICA_URLS, the barrier polls every replica with the full
budget before settling, and up.sh refuses to boot without DD_API_KEY, since the
gateway config enables the datadog callback on every run
