improved performance and battery usage on older devices

lib/state/app/modules/timetable/bloc/timetable_bloc.dart

@@ -133,11 +133,7 @@ class TimetableBloc
 
   Future<void> _refreshSubjects() async {
     final subjects = await repo.data.getSubjects(renew: true);
-    add(
-      DataGathered(
-        (s) => s.copyWith(subjects: subjects, dataVersion: s.dataVersion + 1),
-      ),
-    );
+    add(DataGathered((s) => s.withReferenceData(subjects: subjects)));
   }
 
   Future<void> _loadCurrentWeek(
@@ -177,12 +173,11 @@ class TimetableBloc
 
       add(
         Emit(
-          (s) => s.copyWith(
+          (s) => s.withReferenceData(
             rooms: rooms,
             subjects: subjects,
             schoolHolidays: schoolHolidays,
             schoolyear: schoolyear,
-            dataVersion: s.dataVersion + 1,
           ),
         ),
       );
@@ -192,11 +187,7 @@ class TimetableBloc
 
     try {
       final timegrid = await repo.data.getTimegrid(renew: renew);
-      add(
-        Emit(
-          (s) => s.copyWith(timegrid: timegrid, dataVersion: s.dataVersion + 1),
-        ),
-      );
+      add(Emit((s) => s.withReferenceData(timegrid: timegrid)));
     } catch (_) {
       // Timegrid load failure falls back to a hardcoded schedule in the UI layer.
     }
@@ -212,12 +203,7 @@ class TimetableBloc
         renew: renew,
         onError: onError,
       );
-      add(
-        Emit(
-          (s) =>
-              s.copyWith(customEvents: events, dataVersion: s.dataVersion + 1),
-        ),
-      );
+      add(Emit((s) => s.withReferenceData(customEvents: events)));
     } catch (e) {
       onError?.call(e);
     }
@@ -225,11 +211,7 @@ class TimetableBloc
 
   Future<void> _refreshCustomEvents() async {
     final events = await repo.data.getCustomEvents(renew: true);
-    add(
-      DataGathered(
-        (s) => s.copyWith(customEvents: events, dataVersion: s.dataVersion + 1),
-      ),
-    );
+    add(DataGathered((s) => s.withReferenceData(customEvents: events)));
   }
 
   void _prefetchAdjacentWeeks(DateTime start, DateTime end) {