kept state from previously tombstoned agents — recreating an agent
with the same name reuses it.
live cpu + memory per agent container, from cgroup v2 on the host. cpu
is % of total host capacity (all cores), sampled over ~200ms each
refresh; polled every 5s while this tab is open. network is omitted on
purpose — agents share the host netns, so there is no per-container
counter (see docs/networking/network.md).