Shaped like Statuspage v2, so a dashboard or bot that already watches a status page works
against Foxl with only the host changed. Every response is public, CORS-open, and served from
a precomputed snapshot, so polling it costs us one indexed row read at most.
Two extensions to the Statuspage shape
monitoring reports the freshness of the monitoring itself
(stale, age_ms, measured_at). Alarm on it: a status page
whose own cron has died otherwise reports green forever.
unknown can appear as an indicator and as a component status, meaning the probe
could not establish either state. Code that treats anything other than
operational as not-fine handles it correctly.