implemented recurrence exception (EXDATE) support for custom events, refactored timetable break and holiday generation logic, and refined RRule editor UI/theming and tile layouts

lib/view/pages/timetable/data/calendar_logic.dart

@@ -106,10 +106,21 @@ partitionAppointmentsForWeek(
       final parsed = RecurrenceRule.fromString(rule);
       final anchorUtc = a.startTime.toUtc();
       final duration = a.endTime.difference(a.startTime);
+      // Day-keyed set of exception dates so occurrences scheduled for one
+      // of them get skipped. Syncfusion's own recurrenceExceptionDates
+      // handling never runs because we expand the rule manually here.
+      final exceptionDayKeys = (a.recurrenceExceptionDates ?? const <DateTime>[])
+          .map((d) => '${d.year}-${d.month}-${d.day}')
+          .toSet();
       for (final occUtc in parsed.getInstances(start: anchorUtc)) {
         if (!occUtc.isBefore(weekEndUtc)) break;
         if (occUtc.isBefore(weekStartUtc)) continue;
         final occLocal = occUtc.toLocal();
+        if (exceptionDayKeys.contains(
+          '${occLocal.year}-${occLocal.month}-${occLocal.day}',
+        )) {
+          continue;
+        }
         final idx = DateTime(
           occLocal.year,
           occLocal.month,