BLK-013 fix-forward. Step 1 checked `node >=22` but never verified npm.
On a host where node was already recent, NODE_OK short-circuited the
installer and npm was never touched — yet GSD (gsd-pi) and ctx7 install
via `npm install -g`, so a missing npm made `make plugin` die Error 127
mid-run (distro `apt install nodejs` can ship npm as a separate package).
Add an unconditional npm guard right after the Node block:
corepack enable npm → distro package-manager install fallback → fatal
exit 1 with an actionable message if still absent. Happy path (npm
present) skips the whole block: zero behavior change on healthy machines.
shellcheck clean (only pre-existing SC1091 infos), bash -n OK. Fresh
npm-less apt host validation still pending. Closes TODO (a) 2026-06-30.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VeBXkDr74N9whdiJyjzyVN
