add booking_calendar.loaded class when calendar has loaded

components/calendar.tsx

@@ -94,7 +94,7 @@ export default function MyCalendar({
   return (
     <div className={className}>
       <h2 className="text-xl">Belegungsplan</h2>
-      <Loading loading={daysBookedLoading}>
+      <Loading className="booking_calendar" loading={daysBookedLoading}>
         <Calendar
           defaultActiveStartDate={startDate}
           minDate={new Date()}