Runs the installer's real node_deps_workspace_args against fabricated
checkout layouts by sourcing install.sh in --manifest mode, which defines
its functions without performing an install.
The load-bearing assertion is the invariant that no checkout shape lets
apps/desktop resolve, including the empty-argument case that would silently
hand npm the whole workspace glob back.
Also cover classify_changes recovering the PR file list when compare
returns nothing, so fail-open does not demand ci-reviewed for a CLI-only
install change.
59c5bd0913