Update SearXNG, Gluetun, and Valkey to describe the quadlet units instead of compose: searxng sets Network=gluetun.container, the units install to ~/.config/containers/systemd/, and scripts/deploy-searxng-quadlet.sh deploys them. Add a Boot Persistence section to the Stack doc. Correct the Gluetun tunnel check (the :8000 server 404s; verify tun0 instead) and note the pinned 10.89.2.0/24 subnet.