Backs the new chart above /admin/system-status. Reads HostMetric rows
captured by the per-minute sampler and returns the window the chart
asks for via `?since=` (30m / 1h / 2h / 6h / 12h / 24h, default 2h).
Per-row response shape is what Recharts can plot directly:
- capturedAt ISO-8601
- loadAvg1 number
- memUsedPercent 0..100, rounded to 2 decimals
- diskReadBps / diskWriteBps number | null
Disk fields are derived server-side from the cumulative byte counters
the sampler captured. Computing the per-second delta in the route
keeps the chart component stateless and means a hypothetical CLI / iOS
admin view gets the same units. The first row in any window has no
predecessor, so disk fields are null. A negative delta — counter reset
on host reboot — also surfaces as null instead of a misleading negative
BPS spike.
`meta.memTotalBytes` carries the most recent total so the tooltip can
render an absolute "4.2 GiB / 8 GiB" without a second round-trip.
requireAdmin()-gated: host telemetry is admin-only, never exposed via
Bearer tokens. apiHandler wrapper handles the wide-event annotation
("admin.host-metrics.list") and request-id propagation for free.
6 integration tests against the testcontainer Postgres pin auth
gating, the 2h default window, the diskBps derivation across a
counter-reset, the `?since=30m` filter, and the empty-DB happy path.
