Get host summary

Current CPU usage. WIRE FORMAT IS FROZEN: percent is a NUMBER here, unlike /api/cpu/history where it is a string. Do not "fix" this.

Current-only host status: uptime plus swap (no history series).

Host load average (1 / 5 / 15 minute).

WIRE FORMAT IS FROZEN. usedPercent is the only camelCase key in the API.

Network throughput as a rate (bytes/sec), for host and per-container network endpoints. Rates rather than raw counters, so they downsample by mean.