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

lib/view/pages/settings/sections/timetable_section.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 
+import '../../../../routing/app_routes.dart';
 import '../../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../../utils/haptics.dart';
 import '../../../../view/pages/timetable/data/timetable_name_mode.dart';
@@ -56,6 +57,12 @@ class TimetableSection extends StatelessWidget {
             },
           ),
         ),
+        ListTile(
+          leading: const Icon(Icons.palette_outlined),
+          title: const Text('Fach-Farben'),
+          trailing: const Icon(Icons.chevron_right),
+          onTap: () => AppRoutes.openSubjectColors(context),
+        ),
       ],
     );
   }