feat(ilx): add server-side aspects; restore treefmt formatter; lint clean
Completes the dendritic ilx library begun in a2fb8af.
- Server/infra aspects: server-base, web-gateway, nfs-{server,client},
monitoring, infra-networking, harden-{audit,disk,fail2ban,kernel,
no-defaults,noexec,sshd,sudo,usbguard}, restic-backup, postgres-server,
impermanence, mosquitto, zigbee2mqtt, atticd, auto-upgrade, dns, git-ssh,
locale, nix-defaults.
- Restore the treefmt formatter dropped in the conversion: re-add treefmt-nix
+ modules/formatter.nix (nixfmt + yamlfmt), and switch dendritic.nix to
flake-file's .dendritic flakeModule. It was .default, which regenerated a
broken `outputs = import ./outputs.nix` and failed check-flake-file.
- statix (empty-pattern, inherit) and nixfmt clean across all aspects.
- Drop the empty, unreferenced overlays/default.nix.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>