Zero-mission-arg launch of the build-steam exe -> lands in the glass FE
menu, where Steam sessions actually form (host or join an ISteamMatchmaking
lobby; there is no address to dial, so this is a LAUNCHER not a joiner --
unlike join.bat/join_lan.bat). Sets BT_PLATFORM=glass + BT_STEAM_NET=1,
logs to content\steam.log. Guarded like the sibling bats, with the two
failure modes spelled out (zip without build-steam\; Steam client not
running = menu works, no lobbies).
Requires distributing the build-steam variant (BT_GLASS+BT_STEAM) alongside
content\ -- a different zip shape; the pod-build zips are unaffected. For
dev testers to exercise the Steam path further (prior tests were buggy);
NOT for general players yet: the live 2-machine exit criterion
(docs/STEAM_TEST.md) is still open and the AppID is the 480 test id.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
