machines.json plus Add-machine UI place copies on the least-loaded host.
Monitor samples processing RTT and displays min, avg, p50, and p90 for
capacity planning. Remote hosts run src/agent.js.
Central fleet.json sets min/max copies. Tree-node keepFloor respawns
until three healthy unpaused replicas remain. CLI and loopback UI
pause, resume, stop, and restart instances that fail health checks.
