Day layer (the lib's ODS `Calendar` — react-day-picker v9 wrapper) + a day heading and a scrollable time-chip grid of `Button`s. `startMonth`/`endMonth` pin navigation to [current, current + `MAX_MONTH_OFFSET`] (the past is unreachable); days without slots render disabled/muted. Exports `dayKeyInZone(ms, timeZone)` (parent auto-selects the first available day) and the per-region skeletons — `CalendarSkeleton`, `TimeChipsSkeleton`, and `SlotPickerSkeleton` (the ONLY loading visual for the slot area; every loading path composes these, fixed min-heights, zero layout shift). All instants are epoch-ms; labels render in the parent-resolved zone (this component never reads Intl zone itself). See [`docs/EMBEDDING_HUBSPOT_MEETINGS.md`](../../../docs/EMBEDDING_HUBSPOT_MEETINGS.md).