Pure formatting (nixfmt/prettier/yamlfmt); no behavior change. These
files predate the current treefmt config and were failing nix flake
check; reformatting them makes the gate green again.
Grafana dashboard (auto-provisioned from the dashboards dir) tracks
borgbackup job health, time since last run, and per-job systemd state
from the node_exporter systemd collector on the client. New docs page
covers the ns1 -> control topology, secrets flow, and restore commands.