simplified code across the app and consolidated duplicated helpers

lib/view/pages/timetable/widgets/timetable_calendar_view.dart

@@ -7,6 +7,7 @@ import '../../../../extensions/date_time.dart';
 import '../../../../state/app/modules/capabilities/bloc/capabilities_cubit.dart';
 import '../../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../../state/app/modules/timetable/bloc/timetable_state.dart';
+import '../../../../state/app/modules/timetable/bloc/timetable_week_loader.dart';
 import '../data/arbitrary_appointment.dart';
 import '../data/lesson_period_schedule.dart';
 import '../data/timetable_appointment_factory.dart';
@@ -63,12 +64,10 @@ class TimetableCalendarViewState extends State<TimetableCalendarView> {
   List<TimeRegion>? _regions;
   Object? _regionsKey;
 
-  DateTime _initialDisplayDate() => DateTime.now().addDays(2);
-
   /// Snaps the calendar back to the current week. Exposed so host pages can
   /// wire it to a "today" AppBar action.
   void jumpToToday() {
-    _calendarKey.currentState?.jumpToDate(_initialDisplayDate());
+    _calendarKey.currentState?.jumpToDate(timetableAnchorDate());
   }
 
   List<Appointment> _appointments(TimetableState state) {
@@ -161,7 +160,7 @@ class TimetableCalendarViewState extends State<TimetableCalendarView> {
       schedule: schedule,
       appointments: appointments,
       timeRegions: regions,
-      initialDate: _initialDisplayDate(),
+      initialDate: timetableAnchorDate(),
       minDate: minDate,
       maxDate: maxDate,
       onAppointmentTap: widget.onAppointmentTap,
@@ -197,16 +196,14 @@ class TimetableCalendarViewState extends State<TimetableCalendarView> {
       baseMin = now.subtractDays(14);
       baseMax = now.addDays(7);
     }
-    final effectiveMin = state.accessibleStartDate != null
-        ? (state.accessibleStartDate!.isAfter(baseMin)
-              ? state.accessibleStartDate!
-              : baseMin)
-        : baseMin;
-    final effectiveMax = state.accessibleEndDate != null
-        ? (state.accessibleEndDate!.isBefore(baseMax)
-              ? state.accessibleEndDate!
-              : baseMax)
-        : baseMax;
+    final accessibleStart = state.accessibleStartDate;
+    final accessibleEnd = state.accessibleEndDate;
+    final effectiveMin = accessibleStart == null
+        ? baseMin
+        : _later(accessibleStart, baseMin);
+    final effectiveMax = accessibleEnd == null
+        ? baseMax
+        : _earlier(accessibleEnd, baseMax);
     final today = DateTime.now().dateOnly;
     final todayMonday = today.mondayOfWeek;
     final currentWeekEnd = todayMonday.addDays(DateTime.daysPerWeek - 1);
@@ -216,12 +213,12 @@ class TimetableCalendarViewState extends State<TimetableCalendarView> {
     final capMax = futureDays == null
         ? null
         : _later(today.addDays(futureDays), currentWeekEnd);
-    final cappedMin = capMin != null && effectiveMin.isBefore(capMin)
-        ? capMin
-        : effectiveMin;
-    final cappedMax = capMax != null && effectiveMax.isAfter(capMax)
-        ? capMax
-        : effectiveMax;
+    final cappedMin = capMin == null
+        ? effectiveMin
+        : _later(effectiveMin, capMin);
+    final cappedMax = capMax == null
+        ? effectiveMax
+        : _earlier(effectiveMax, capMax);
     // When the resulting range does not cover the current week — the summer gap
     // between two school years, or a stale persisted bound — fall back to the
     // current week, widened to whatever the capabilities still allow. Otherwise