searchStates method
Implementation
List<StateModel> searchStates(String query, String? countryId) {
if (_states == null) return [];
final lowerQuery = query.toLowerCase();
var filteredStates = _states!.where((state) =>
state.name.toLowerCase().contains(lowerQuery)
);
if (countryId != null) {
filteredStates = filteredStates.where((state) => state.countryId == countryId);
}
return filteredStates.toList();
}