fix: correct Flex Query API hostname and endpoint paths

[proschu2]

Problem

The Flex Query client was using incorrect hostname and API paths, causing DNS resolution errors:

• Wrong hostname: gdcdyn.interactivebrokers.com (does not exist)
• Wrong base path: /Universal/servlet
• Wrong endpoints: /FlexStatementService.SendRequest, /FlexStatementService.GetStatement

Error: EAI_AGAIN gdcdyn.interactivebrokers.com

Solution

Updated to match IBKR Flex Web Service v3 API documentation:

• Fixed hostname: ndcdyn.interactivebrokers.com
• Fixed base path: /AccountManagement/FlexWebService
• Fixed endpoints: /SendRequest, /GetStatement

Correct API Format

https://ndcdyn.interactivebrokers.com/AccountManagement/FlexWebService/SendRequest?t={Token}&q={QueryID}&v=3

Reference

• IBKR API Docs: https://www.interactivebrokers.com/en/software/am/am/reports/flex_web_service_version_3.htm
• Tested with valid Flex Token and Query ID

[NitayRabi]

Thanks for the fix! The test failures were due to the tests using the old URLs. I've created #23 with the complete fix including updated tests.