Bun:Node + npm + Vite + Vitest, all in one binary

Not in use. If we ever switch, the two first targets are api.cuberoot.me (Hono on Bun beats Node) and the one-off TS scripts under core/scripts/ (bun run is 2-3x faster cold start than tsx). The current pm2 + Node 22 setup is fine, so it stays.