refactor(dashboard): Use constants for IDs

- Replaced hardcoded IDs with constants.
- Improved code readability and maintainability.
- Reduced risk of ID mismatch errors.
- Updated `dashboard_bloc.dart` file.
- Used `kDashboardSummaryId` and `kRemoteConfigId`.

Author: fulleni

lib/dashboard/bloc/dashboard_bloc.dart

@@ -2,6 +2,7 @@ import 'package:bloc/bloc.dart';
 import 'package:equatable/equatable.dart';
 import 'package:ht_data_repository/ht_data_repository.dart';
 import 'package:ht_shared/ht_shared.dart';
+import 'package:ht_shared/src/constants/fixture_ids.dart';
 
 part 'dashboard_event.dart';
 part 'dashboard_state.dart';
@@ -36,8 +37,8 @@ class DashboardBloc extends Bloc<DashboardEvent, DashboardState> {
         appConfigResponse,
         recentHeadlinesResponse,
       ] = await Future.wait([
-        _dashboardSummaryRepository.read(id: 'dashboard_summary'),
-        _appConfigRepository.read(id: 'app_config'),
+        _dashboardSummaryRepository.read(id: kDashboardSummaryId),
+        _appConfigRepository.read(id: kRemoteConfigId),
         _headlinesRepository.readAll(
           pagination: const PaginationOptions(limit: 5),
           sort: const [SortOption('createdAt', SortOrder.desc)],