pypsrp's execute_ps is fully blocking, so Install-CIToolchain / Windows
Update output only appeared at the end behind a "still running (Ns)"
heartbeat. Add WinRmTransport.run_streaming: drive the script via pypsrp's
incremental begin_invoke/poll_invoke, emitting output, Write-Host
(information) and error stream lines as they arrive over the same WinRM
channel.
_run_with_heartbeat now prefers run_streaming (suppressing the CI_EXITCODE
marker line) and falls back to the blocking heartbeat only on an unexpected
pypsrp error — TransportError still propagates so the 3010 reboot handling
is unaffected.