Apply suggestions from code review

lib/game/components/backbox/bloc/backbox_state.dart

@@ -58,7 +58,7 @@ class InitialsSuccessState extends BackboxState {
   List<Object?> get props => [];
 }
 
-/// State when the leaderboard was successfully loaded
+/// State when the leaderboard was successfully loaded.
 class InitialsFailureState extends BackboxState {
   @override
   List<Object?> get props => [];

lib/game/components/backbox/displays/initials_submission_failure_display.dart

@@ -13,7 +13,7 @@ final _bodyTextPaint = TextPaint(
 );
 
 /// {@template initials_submission_failure_display}
-/// Display when the initials failed to submitted
+/// Display when the initials failed to submitted.
 /// {@endtemplate}
 class InitialsSubmissionFailureDisplay extends TextComponent
     with HasGameRef<PinballGame> {