Updates to Separator

• Schedules: events can carry an eventEndAtUtc (and venue-local eventEndDateKey). Rows render a finish time (7pm – 11pm) or a multi-day range (6:30pm – Sun 4 Oct, 9pm) via the new shared formatEventSchedule / formatDayShort core helpers. Existing data without end fields is unchanged (start time only). - Reserved seats: CartTicket.seats takes structured CartSeat[] (section / row / seat). The new shared formatSeatRange core helper groups by section + row and collapses consecutive seats into a range (e.g. Stalls B11–12, Mezzanine M3 · Circle C5), so every skin and consumer renders seating identically. Shown as a seat-icon badge beside the ticket name. - Same-day events are separated by a hairline divider; event and day-group removals animate height + opacity, and the header urgency badge splits into a ticket-count badge and a separate countdown badge that animates in/out and hides when the cart is empty. - Header/footer spacing, the drag handle, container-query event images, and the remove-confirm popover arrow are refined to match across both skins.

All additions are backward compatible — the new CartEvent / CartTicket fields are optional and the new core exports are additive.

The base border applied a width to all four sides, so with h-px the top and bottom borders both painted and read as ~2px. The colour and style now live in the base and each orientation sets a single-side width (border-t / border-l).