fixed overwrite on internal copy, DST drift in widget anchors, inline errors without controller and removed dead room lookup

lib/background/widget_background_task.dart

@@ -9,14 +9,13 @@ import '../api/marianumconnect/marianumconnect_endpoint.dart';
 import '../api/marianumconnect/queries/timetable_custom_events/timetable_custom_events_get.dart';
 import '../api/marianumconnect/queries/timetable_get_holidays/timetable_get_holidays.dart';
 import '../api/marianumconnect/queries/timetable_get_holidays/timetable_get_holidays_response.dart';
-import '../api/marianumconnect/queries/timetable_get_rooms/timetable_get_rooms.dart';
-import '../api/marianumconnect/queries/timetable_get_rooms/timetable_get_rooms_response.dart';
 import '../api/marianumconnect/queries/timetable_get_subjects/timetable_get_subjects.dart';
 import '../api/marianumconnect/queries/timetable_get_subjects/timetable_get_subjects_response.dart';
 import '../api/marianumconnect/queries/timetable_get_timegrid/timetable_get_timegrid.dart';
 import '../api/marianumconnect/queries/timetable_get_timegrid/timetable_get_timegrid_response.dart';
 import '../api/marianumconnect/queries/timetable_get_week/timetable_get_week.dart';
 import '../api/mhsl/custom_timetable_event/get/get_custom_timetable_event_response.dart';
+import '../extensions/date_time.dart';
 import '../session/session_manager.dart';
 import '../widget_data/widget_data_mapper.dart';
 import '../widget_data/widget_publisher.dart';
@@ -151,9 +150,7 @@ Future<void> _refresh() async {
   // Fetch window matches the week payload's window so the widget can roll
   // forward into next week's lessons without fresh data.
   final weekStart = WidgetDataMapper.startOfCalendarWeek(now);
-  final weekEndExclusive = weekStart.add(
-    const Duration(days: WidgetDataMapper.weekWindowDays),
-  );
+  final weekEndExclusive = weekStart.addDays(WidgetDataMapper.weekWindowDays);
 
   // All six requests are independent — run them concurrently so the total
   // latency is the slowest request, not the sum (matters for the push path's
@@ -161,14 +158,11 @@ Future<void> _refresh() async {
   // mapper rather than aborting the whole refresh.
   final timetableFuture = TimetableGetWeek().run(
     from: weekStart,
-    until: weekEndExclusive.subtract(const Duration(days: 1)),
+    until: weekEndExclusive.subtractDays(1),
   );
   final subjectsFuture = _runOrNull<TimetableGetSubjectsResponse>(
     () => TimetableGetSubjects().run(),
   );
-  final roomsFuture = _runOrNull<TimetableGetRoomsResponse>(
-    () => TimetableGetRooms().run(),
-  );
   final holidaysFuture = _runOrNull<TimetableGetHolidaysResponse>(
     () => TimetableGetHolidays().run(),
   );
@@ -180,7 +174,6 @@ Future<void> _refresh() async {
   );
   final timetable = await timetableFuture;
   final subjects = await subjectsFuture;
-  final rooms = await roomsFuture;
   final holidays = await holidaysFuture;
   final timegrid = await timegridFuture;
   final customEvents = await customEventsFuture;
@@ -193,7 +186,6 @@ Future<void> _refresh() async {
     now: now,
     lessons: timetable.entries,
     subjects: subjects,
-    rooms: rooms,
     holidays: holidays,
     timegrid: timegrid,
     customEvents: customEvents,