The fan-ceiling check, the webui metrics collector (every 5s) and the PSU
health poller each shelled out to ipmitool independently. The BMC's KCS
interface serializes those calls anyway, so under load the concurrent
`ipmitool sdr`/`dcmi power reading` invocations just queued behind each
other — that's what produced "IPMI slow" backoff during a fan-ceiling run in
a blackbox dump, while the dashboard looked fine only because it was reading
its own, separately-stale data from a different ipmitool call.
hw_telemetry.go is now the sole recurring poller (fan RPM, temperature, PSU
power/status, DCMI system power), with the adaptive 1s-30s backoff that used
to be duplicated inside the fan check. Every hot-path consumer reads the
shared cache (hwSnapshot / platform.HardwareSDRSnapshot) instead of calling
ipmitool itself.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
