Anonymous visitors to a public status page have no persisted Redux
state, so ThemedHeatmap and ThemedHistogram tooltips always rendered
timestamps in the hardcoded "America/Toronto" default — regardless of
the timezone the operator configured. Even on the same domain,
ThemedHeatmap and ThemedHistogram had no code path to consume the
operator-configured statusPage.timezone returned by the API.
- Add SYSTEM_TIMEZONE module constant and a small resolveTimezone()
helper to TimeUtils.ts. formatDateWithTz's timezone parameter is now
optional and defaults to the system tz, so callers don't need to
rebuild the prop -> browser -> UTC chain inline.
- Add a `timezone` field to StatusPageThemeContextValue so any themed
component on the public page can read the page-wide tz without prop
drilling (parallels how `theme` and `mode` are already exposed).
- Wire statusPage.timezone into StatusPageThemeProvider from
Pages/StatusPage/Status/index.tsx (both the public route and the
admin preview).
- ThemedHeatmap and ThemedHistogram now read tz from the context
instead of useSelector(state.ui.timezone) — that selector was
unreliable for anonymous visitors and removing it cuts a Redux
subscription on the public page.
- Replace the inline `data?.timezone || Intl.DateTimeFormat()...`
expression in useStatusPageForm.ts with resolveTimezone().
Closes#3628.
gorkem-bwl
1458cf4e4a