implemented custom subject colors for the timetable and unified the color palette system

lib/view/pages/timetable/details/custom_event_sheet.dart

@@ -1,18 +1,22 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:rrule/rrule.dart';
 
 import '../../../../api/mhsl/custom_timetable_event/custom_timetable_event.dart';
 import '../../../../extensions/date_time.dart';
+import '../../../../state/app/modules/timetable/bloc/timetable_bloc.dart';
 import '../../../../widget/centered_leading.dart';
 import '../../../../widget/debug/debug_tile.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../custom_events/custom_event_edit_dialog.dart';
 import '../data/rrule_with_exceptions.dart';
+import '../subject_colors/subject_color_picker.dart';
 import 'delete_custom_event.dart';
 
 class CustomEventSheet {
   static void show(BuildContext context, CustomTimetableEvent event) {
     final timeRange = event.startDate.timeRangeTo(event.endDate);
+    final bloc = context.read<TimetableBloc>();
 
     showDetailsBottomSheet(
       context,
@@ -23,6 +27,12 @@ class CustomEventSheet {
           style: const TextStyle(fontWeight: FontWeight.bold),
         ),
         subtitle: Text(timeRange),
+        trailing: TimetableColorHeaderButton(
+          initialColorName: event.color,
+          pickerTitle: 'Farbe wählen',
+          onSelected: (option) =>
+              bloc.updateCustomEvent(event.id, _withColor(event, option.name)),
+        ),
       ),
       children: (sheetCtx) => [
         Padding(
@@ -104,4 +114,18 @@ class CustomEventSheet {
       ],
     );
   }
+
+  static CustomTimetableEvent _withColor(CustomTimetableEvent e, String color) =>
+      CustomTimetableEvent(
+        id: e.id,
+        title: e.title,
+        description: e.description,
+        startDate: e.startDate,
+        endDate: e.endDate,
+        color: color,
+        rrule: e.rrule,
+        skipHolidays: e.skipHolidays,
+        createdAt: e.createdAt,
+        updatedAt: DateTime.now(),
+      );
 }