refactor: correct spelling and enhance PreparationStepWithTime handling

- Renamed PreprationStepWithTime to PreparationStepWithTime for consistency.
- Updated methods to use the new class name and improved elapsed time handling with a copyWithElapsed method.
- Ensured proper casting of preparation step lists in ScheduleBloc and ScheduleState.

Author: jjoonleo

lib/presentation/app/bloc/schedule/schedule_bloc.dart

@@ -119,8 +119,9 @@ class ScheduleBloc extends Bloc<ScheduleEvent, ScheduleState> {
 
   PreparationStepEntity _findCurrentPreparationStep(
       ScheduleWithPreparationEntity schedule, DateTime now) {
-    final List<PreprationStepWithTime> steps =
-        schedule.preparation.preparationStepList.cast<PreprationStepWithTime>();
+    final List<PreparationStepWithTime> steps = schedule
+        .preparation.preparationStepList
+        .cast<PreparationStepWithTime>();
 
     if (steps.isEmpty) {
       throw StateError('Preparation steps are empty');
@@ -135,25 +136,23 @@ class ScheduleBloc extends Bloc<ScheduleEvent, ScheduleState> {
 
     Duration elapsed = now.difference(preparationStartTime);
 
-    for (final PreprationStepWithTime step in steps) {
+    for (final PreparationStepWithTime step in steps) {
       if (elapsed < step.preparationTime) {
-        step.elapsedTime = elapsed;
-        return step;
+        return step.copyWithElapsed(elapsed);
       }
       elapsed -= step.preparationTime;
-      step.elapsedTime = step.preparationTime;
     }
 
     // If elapsed exceeds total preparation duration (e.g., during move/spare time),
     // return the last preparation step as current by convention.
-    return steps.last;
+    return steps.last.copyWithElapsed(steps.last.preparationTime);
   }
 
   ScheduleWithPreparationEntity _convertToScheduleWithTimePreparation(
       ScheduleWithPreparationEntity schedule) {
     final preparationWithTime = PreparationWithTime(
       preparationStepList: schedule.preparation.preparationStepList
-          .map((step) => PreprationStepWithTime(
+          .map((step) => PreparationStepWithTime(
                 id: step.id,
                 preparationName: step.preparationName,
                 preparationTime: step.preparationTime,

lib/presentation/app/bloc/schedule/schedule_state.dart

@@ -52,31 +52,41 @@ class ScheduleState extends Equatable {
   List<Object?> get props => [status, schedule];
 }
 
-class PreprationStepWithTime extends PreparationStepEntity
+class PreparationStepWithTime extends PreparationStepEntity
     implements Equatable {
-  Duration elapsedTime;
+  final Duration elapsedTime;
 
-  PreprationStepWithTime({
+  const PreparationStepWithTime({
     required super.id,
     required super.preparationName,
     required super.preparationTime,
     required super.nextPreparationId,
     this.elapsedTime = Duration.zero,
   });
 
+  PreparationStepWithTime copyWithElapsed(Duration elapsed) {
+    return PreparationStepWithTime(
+      id: id,
+      preparationName: preparationName,
+      preparationTime: preparationTime,
+      nextPreparationId: nextPreparationId,
+      elapsedTime: elapsed,
+    );
+  }
+
   @override
   List<Object?> get props =>
       [id, preparationName, preparationTime, nextPreparationId, elapsedTime];
 }
 
 class PreparationWithTime extends PreparationEntity implements Equatable {
   const PreparationWithTime({
-    required List<PreprationStepWithTime> preparationStepList,
+    required List<PreparationStepWithTime> preparationStepList,
   }) : super(preparationStepList: preparationStepList);
 
   @override
-  List<PreprationStepWithTime> get preparationStepList =>
-      super.preparationStepList.cast<PreprationStepWithTime>();
+  List<PreparationStepWithTime> get preparationStepList =>
+      super.preparationStepList.cast<PreparationStepWithTime>();
 
   @override
   List<Object?> get props => [preparationStepList];