fix: clear stale auth flags and improve user name fallback logic (#637)

- Clear AuthTokenStore in _silentSessionRecovery when session is invalid (Case 2)

- Use .trim().isNotEmpty for userName fallback to handle empty strings (Case 1)

userfront/lib/features/dashboard/presentation/dashboard_screen.dart

@@ -846,11 +846,13 @@ class _DashboardScreenState extends ConsumerState<DashboardScreen> {
       final profileState = ref.watch(profileProvider);
       final profile = profileState.value;
       final timelineState = ref.watch(authTimelineProvider);
-      final userName =
-          profile?.name ??
-          profile?.email ??
-          profile?.phone ??
-          tr('ui.userfront.profile.user_fallback', fallback: 'User');
+      final userName = (profile?.name.trim().isNotEmpty ?? false)
+          ? profile!.name
+          : (profile?.email.trim().isNotEmpty ?? false)
+              ? profile!.email
+              : (profile?.phone.trim().isNotEmpty ?? false)
+                  ? profile!.phone
+                  : tr('ui.userfront.profile.user_fallback', fallback: 'User');
       final departmentValue =
           profile?.tenant?.name ?? profile?.department ?? '';
       final department = departmentValue.isNotEmpty