replaced account data singleton with a session model

lib/view/pages/settings/diagnostics_page.dart

@@ -13,10 +13,11 @@ import '../../../api/marianumconnect/marianumconnect_endpoint.dart';
 import '../../../api/marianumconnect/queries/telemetry_heartbeat/telemetry_device_id.dart';
 import '../../../background/widget_background_task.dart';
 import '../../../extensions/date_time.dart';
-import '../../../model/account_data.dart';
 import '../../../model/endpoint_data.dart';
 import '../../../push/push_registration_store.dart';
 import '../../../push/push_registration_type.dart';
+import '../../../session/session.dart';
+import '../../../session/session_manager.dart';
 import '../../../state/app/modules/account/bloc/account_bloc.dart';
 import '../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../utils/clipboard_helper.dart';
@@ -44,7 +45,8 @@ class _DiagnosticsPageState extends State<DiagnosticsPage> {
   Future<List<_Section>> _collect() async {
     final settings = context.read<SettingsCubit>().val();
     final accountStatus = context.read<AccountBloc>().state.status;
-    final account = AccountData();
+    final session = SessionManager().current;
+    final nextcloud = session?.nextcloud;
     const tokens = MarianumConnectTokenStorage();
     final push = PushRegistrationStore();
 
@@ -101,13 +103,17 @@ class _DiagnosticsPageState extends State<DiagnosticsPage> {
         title: 'Sitzung',
         rows: await rows({
           'Status': () async => accountStatus.name,
-          'Benutzer': () async =>
-              account.isPopulated() ? account.getUsername() : null,
-          'Demo-Modus': () async => account.isDemo,
-          'Login Flow v2': () async => account.usesLoginFlow,
-          'App-Passwort (Dateien)': () async => account.hasAppPassword(),
-          'App-Passwort (Talk)': () async => account.hasAppPasswordTalk(),
-          'Session-Epoche': () async => account.sessionEpoch,
+          'Benutzer': () async => switch (session) {
+            CredentialSession(:final username) => username,
+            null => null,
+          },
+          'Demo-Modus': () async => session?.isDemo ?? false,
+          'Login Flow v2': () async => nextcloud?.usesLoginFlow ?? false,
+          'App-Passwort (Dateien)': () async =>
+              nextcloud?.hasAppPassword ?? false,
+          'App-Passwort (Talk)': () async =>
+              nextcloud?.hasAppPasswordTalk ?? false,
+          'Session-Epoche': () async => SessionManager().sessionEpoch,
           'MC-Token-ID': tokens.readTokenId,
           'MC-Token läuft ab': tokens.readExpiresAt,
         }),