Lane=Live end-to-end verification against the real feed, using the production
updater the GUI button calls: ReleaseManifestClient.ProductionManifestUri, real
network, real SHA-256/size verification, real ZIP extraction, real atomic
activation. Asserts what the launcher actually does next — that
LauncherExecutableSet can resolve BOTH hosts out of the activated directory,
and that current.json names the installed version — rather than merely that
files exist.
Excluded from the bounded gate (Lane=Live needs the public feed reachable);
run deliberately after a release lands. Writes only under an isolated
temporary path set, never the caller's real launcher data directory.
