refactor container selection pattern and improve search UI

app/lib/features/onboarding/presentation/onboarding.dart

@@ -17,13 +17,13 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
-import 'package:drift/drift.dart' show Value;
 import 'package:flutter/material.dart';
 import 'package:flutter_hooks/flutter_hooks.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:smooth_page_indicator/smooth_page_indicator.dart';
 import 'package:weblibre/core/providers/defaults.dart';
 import 'package:weblibre/core/providers/router.dart';
+import 'package:weblibre/features/geckoview/domain/entities/tab_container_selection.dart';
 import 'package:weblibre/features/geckoview/domain/repositories/tab.dart';
 import 'package:weblibre/features/onboarding/presentation/pages/abstract/i_form_page.dart';
 import 'package:weblibre/features/onboarding/presentation/pages/ai_configuration.dart';
@@ -148,7 +148,8 @@ class OnboardingScreen extends HookConsumerWidget {
                             .addTab(
                               url: ref.read(docsUriProvider),
                               private: false,
-                              container: const Value(null),
+                              containerSelection:
+                                  const TabContainerSelection.unassigned(),
                               selectTab: true,
                             );