Slim follow-up to the salvaged #111790: the helper becomes a list-returning
sibling of _managed_runtime_path_entries (same shape, same "only when it
exists" convention) and loses the Windows check the caller already performs.
Why here and not in the Electron remote spawn: propagating the login-shell PATH
that locateHermes discovered into `exec env HERMES_DESKTOP=1 … hermes serve`
would fix only the Desktop SSH surface; the terminal environment's PATH
completion is the seam every thin-PATH launcher (SSH, systemd, launchd, cron)
already goes through, so the class closes once. Windows twin out of scope.
Tests move to the mirror dir tests/tools/environments/ with an absent-dir
control; FAQ documents the terminal PATH composition.
Fixes#111778
43e7e830fd