refactor(navigation): launch AccountPage from app bar

Updated the onTap action for the user avatar in the FeedSliverAppBar. It no longer shows a modal bottom sheet. Instead, it now navigates to the new top-level /account route using context.pushNamed(Routes.accountName).

Author: fulleni

lib/headlines-feed/widgets/feed_sliver_app_bar.dart

@@ -2,12 +2,13 @@ import 'package:core/core.dart';
 import 'package:data_repository/data_repository.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
-import 'package:flutter_news_app_mobile_client_full_source_code/account/widgets/account_sheet.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/app/bloc/app_bloc.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/headlines-search/bloc/headlines_search_bloc.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/headlines-search/view/headline_search_delegate.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/l10n/l10n.dart';
+import 'package:flutter_news_app_mobile_client_full_source_code/router/routes.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/shared/widgets/user_avatar.dart';
+import 'package:go_router/go_router.dart';
 import 'package:ui_kit/ui_kit.dart';
 
 /// {@template feed_sliver_app_bar}
@@ -74,10 +75,7 @@ class FeedSliverAppBar extends StatelessWidget {
               // The user avatar is also tappable to open the account sheet.
               GestureDetector(
                 onTap: () {
-                  showModalBottomSheet<void>(
-                    context: context,
-                    builder: (_) => const AccountSheet(),
-                  );
+                  context.pushNamed(Routes.accountName);
                 },
                 child: BlocSelector<AppBloc, AppState, User?>(
                   selector: (state) => state.user,