- getUserTodayBounds: a 25h fall-back day keeps a 23:30 dose inside today,
a 23h spring-forward day does not bleed tomorrow's 00:30 dose, ordinary
days stay 24h, and a negative-offset zone anchors on the local day.
- dailyComplianceRatesFromLedger: a Los-Angeles user's two same-local-day
doses land in ONE bucket where the old fixed-Berlin key split them.
- classifyIntakeTiming: an 08:00-local dose reads on_time with the user's
zone and very_late without it.
- hourInTz: reads the wall-clock hour in the given zone.
- hero-strip greeting: resolves the hour in the stored zone, not the
browser clock; existing greeting fixtures re-pinned to explicit UTC
instants mapped to Berlin wall-clock.