searchCities method
Implementation
List<CityModel> searchCities(String query, String? stateId) {
if (_cities == null) return [];
final lowerQuery = query.toLowerCase();
var filteredCities = _cities!.where((city) =>
city.name.toLowerCase().contains(lowerQuery)
);
if (stateId != null) {
filteredCities = filteredCities.where((city) => city.stateId == stateId);
}
return filteredCities.toList();
}