port_login_flow_test gains a `live` mode that runs the same script path
against a real 40250 server and checks the client's own state: the
character list, then LoadingWindow.LoadData from GC_MAIN_CHARACTER (which
CPythonNetworkStream answers with CG_CLIENT_VERSION), exiting before the
game phase. Host, ports, account and slot come only from MT_LIVE_* env
vars, are handed to Python as objects and never printed; without them
the test skips. Not yet run live: the server was unreachable today.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>