Task #662: Google-Calendar-style room booking calendar view

Replaced the Protocol bookings "Calendar" view (previously an agenda list
grouped by day) with a two-panel Google-Calendar layout in
artifacts/tx-os/src/pages/protocol.tsx:
- LEFT: a mini month day-picker (reuses components/ui/calendar.tsx,
  react-day-picker single mode) driving a selectedDay state. Days that
  have bookings get a small sky dot via a `booked` modifier.
- RIGHT: a single-day vertical time-grid (BookingDayGrid) over working
  hours 07:00–22:00 (56px/hour). Bookings render as absolutely-positioned
  blocks: top = start offset, height = duration (min 22px), colored by
  status (BOOKING_BLOCK_STYLE) with an inline-start accent border and a
  title/room/time label.
- Overlapping bookings are laid out side-by-side via interval-partition
  column assignment (layoutDayBookings), chained overlaps share a column
  count.
- A live RED current-time line + red dot (useNow, 60s) shows only when the
  selected day is today and within grid hours.

Details:
- View-only (no drag/create); single-day grid only. No backend changes.
- RTL/i18n: logical props (insetInlineStart, border-s) so it mirrors in
  Arabic; added protocol.bookings.emptyDay to ar.json + en.json.
- Blocks with no visible intersection with the grid range are skipped
  (fixes a phantom-block bug for bookings fully before 7am / after 10pm,
  found in code review).
- Removed the now-unused groupBookingsByDay helper.
- List toggle preserved. tx-os typecheck passes.

artifacts/tx-os/src/locales/en.json

@@ -1596,6 +1596,7 @@
       "endsAt": "To",
       "viewList": "List",
       "viewCalendar": "Calendar",
+      "emptyDay": "No bookings on this day.",
       "shareLinkTitle": "Public booking link (share with guests)",
       "copyLink": "Copy link",
       "linkCopied": "Link copied",