Use writerStreaming() instead of writer() for stdout in helpgen and
main_build_data. The positional writer calls setEndPos/ftruncate in
end(), which fails on Windows because ftruncate on pipes maps
INVALID_PARAMETER to FileTooBig.
Replace scandir with opendir/readdir plus qsort in framegen since
scandir is a POSIX extension not available on Windows.
This was previously applied and reverted upstream (f4998c6ab, 0fdddd5bc)
as collateral from an unrelated example-execution hang that has since
been resolved.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
