sendOtp method
Implementation
Future<void> sendOtp(String phone, {String? countryCode}) async {
final data = await ref.read(authControllerProvider.notifier).sendOtp(phone);
if (data == null) return;
state = state.copyWith(
phone: phone,
countryCode: countryCode,
step: FxPhoneAuthStep.enterOtp,
otpData: data,
);
}