fix(intrade-bar): tolerate transient host check failures

[LimiNode]

Summary

• use GET for the current broker host health check because some proxy/front-end paths reject HEAD-like requests
• require two consecutive failed connected host checks before disconnecting an account
• add diagnostics and a local regression test that distinguishes GET from HEAD

Validation

• MinGW C++17 syntax check for intrade_bar_api_response_test.cpp with the changed headers
• git diff --check

Notes

• full local test execution was not run in this isolated worktree because its submodules were not populated; CI runs the target.