#4655 added amp/copilot/kilo/kimi to the hand-maintained --help install
line but still omitted antigravity-windows, so it disagreed with
_print_install_usage. Derive the list from the same
[*_PLATFORM_CONFIG, "gemini", "cursor"] expression the install usage
uses so the two cannot drift, and add test_help_lists_every_install_platform
to catch any future platform that is not advertised.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
graphify --help omitted the real prs and provider commands and the export format list. Add
them (verbatim from the dispatcher's own usage text), so every listed command/format exists
and the export formats match the supported allow-list.
