kubectl rollout status confirms the pod is ready per readinessProbe, but
Kubernetes Service DNS propagation to the runner pod may lag behind.
This caused intermittent E2E failures with ERR_NAME_NOT_RESOLVED.
Add a poll loop (max 120s) after rollout status that verifies the service
URL is reachable via HTTP before writing .env.e2e. This eliminates the
race condition between DNS propagation and Playwright launch.
Fixes: PRI-687 (intermittent E2E DNS failure)