Deselect day on re-click in single-date mode

room_cal/vue/calendar.html

@@ -1891,6 +1891,11 @@ createApp({
         bulkDays.value = next;
         return;
       }
+      const key = fmtDate(day);
+      if (selection.value?.type === 'day' && selection.value.key === key) {
+        selection.value = null;
+        return;
+      }
       editingBase.value         = null;
       editingDiscount.value     = null;
       pendingDiscountType.value = null;
@@ -1900,7 +1905,7 @@ createApp({
       discountState.value       = 'idle';
       selection.value = {
         type:    'day',
-        key:     fmtDate(day),
+        key,
         date:    day,
         label:   day.toLocaleString('default', { month: 'long', day: 'numeric' }),
         weekday: day.toLocaleString('default', { weekday: 'long' }),