fix: early check-in checkout date capped at original planned checkout

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

src/components/bookings/BookingDetailPanel.tsx

@@ -604,6 +604,7 @@ export function BookingDetailPanel({ booking, room, rooms, allBookings, slug, on
                         className="input text-sm"
                         value={earlyNewCheckOut}
                         min={today}
+                        max={booking.checkOut}
                         onChange={e => setEarlyNewCheckOut(e.target.value)}
                       />
                     </div>