When the installer falls back to a bundled Node under $HERMES_HOME/node,
npm's default global prefix is that Node dir, so `npm install -g <pkg>`
drops the package binary in $HERMES_HOME/node/bin. Only node/npm/npx are
symlinked into the command link dir (~/.local/bin, /usr/local/bin, or
$PREFIX/bin) — so user-installed global package binaries are NOT on PATH
and can't be run, even though `npm i -g` reports success. They also get
wiped on every Node upgrade (the dir is rm -rf'd and re-extracted).
Redirect the bundled Node's npm global prefix to the command link dir's
parent, so global bins land in the link dir (already on PATH, alongside
node/npm/npx) and survive Node upgrades. Scoped to the bundled Node via
its prefix-local global npmrc ($HERMES_HOME/node/etc/npmrc), so the user's
other Node installs and their ~/.npmrc are untouched. Hermes's own global
installs (agent-browser) pass an explicit --prefix and are unaffected.