Add linting, formatting, and CI

- Add deadnix, nixfmt, and statix to flake inputs
- Add formatter output to flake for nix fmt support
- Add deadnix, nixfmt, statix to Home Manager packages
- Format all nix files with nixfmt
- Add GitHub Actions workflow for CI validation
- Support x86_64-darwin in formatter

modules/hosts/nixos/hetznix02/post-install/nginx.nix

@@ -1,7 +1,8 @@
-
-{ pkgs, ... }: let
+{ pkgs, ... }:
+let
   domain = "genebean.me";
-in {
+in
+{
   environment.etc.nginx-littlelinks = {
     # Info generated via
     # nurl https://github.com/genebean/littlelink genebean-sometag