Add "interface type" setting

android/gradle.properties

assets/translations/en.json

assets/translations/fr.json

lib/cubit/settings_cubit.dart

lib/cubit/settings_state.dart

lib/models/interface_type.dart

lib/ui/screens/demo_page.dart

lib/ui/skeleton.dart

lib/ui/widgets/app_bar.dart

lib/ui/widgets/header_app.dart

lib/ui/widgets/settings_form.dart

pubspec.lock

pubspec.yaml