Room planner: fix settings scroll, checkout time to left-bracket sliver

- Settings page: add overflow-y:auto + flex:1 so content scrolls within
  page-content (which has overflow:hidden)

- Checkout time: move departure time out of B2B card stats row and into
  the left-bracket sliver, matching original plugin behaviour:
  - Only shown while prev booking status is still 'arrived' (not yet
    checked out); collapses to normal bracket once NewBook flips to
    'departed'
  - Positioned absolutely over the ::before left bracket area
  - Remove the forced 'departed' override on prev_status — let NewBook's
    real status drive bracket colour so the sliver shows correctly

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/lib/booking-flow.js

@@ -113,12 +113,10 @@ export function classifyRoom(site, allBookings, viewDate, yesterday, tomorrow) {
   // the card right — it ends tonight and its right border should be visible.
   const spansNext = !!primaryBooking && !!departureDate && departureDate > tomorrow
 
-  // Previous-day bracket: if the previous booking departs TODAY, force "departed"
-  // colour regardless of whether NewBook has updated its status yet.
-  const rawPrevStatus = prevBooking ? (prevBooking.booking_status || '').toLowerCase() : null
-  const prevStatus    = (rawPrevStatus && toDateStr(prevBooking?.booking_departure) === viewDate)
-    ? 'departed'
-    : rawPrevStatus
+  // Previous-day bracket: use real NewBook status so the sliver remains 'arrived'
+  // (wide, with checkout time) until the guest actually checks out and NewBook
+  // flips the status to 'departed'. Do not override — let real status drive colour.
+  const prevStatus = prevBooking ? (prevBooking.booking_status || '').toLowerCase() : null
 
   // NewBook may return category info as flat fields or a nested object.
   const catId   = site.site_category_id   ?? site.category_id   ?? site.category?.id   ?? null