b20387dfa9
One semantic conflict on the `all-checks-passed` verdict job. Master moved it to `ubuntu-latest`; this branch had routed it through the failover selector so a hosted-pool outage could not leave the required verdict queued. Master's resolution satisfies that requirement more directly: standard hosted capacity is independent of both custom pools, so the verdict is reachable whichever pool is degraded, and the selector is no longer needed. Kept `ubuntu-latest` and folded the failover reasoning into its comment. The failover runbook accordingly documents three failover jobs (the three required Linux workers), not four, and states why the verdict stays on standard hosted capacity in both states.