verifyPayment method

Implementation

@override
Future<PaymentResponse> verifyPayment(String transactionId) async {
  try {
    final response = await makeBackendRequest(
      endpoint: '/api/payments/verify/$transactionId',
      method: 'GET',
    );

    final data = handleResponse(response);
    return parsePaymentResponse(data);
  } catch (e) {
    return PaymentResponse.failure(
      message: 'Failed to verify payment: $e',
      provider: PaymentProvider.paystack,
    );
  }
}