Add linting, formatting, and CI infrastructure

- 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
- Add GitHub Actions workflow for CI validation
- Add .pre-commit-config.yaml with hooks for nixfmt, deadnix, and statix
- Support x86_64-darwin in formatter

modules/hosts/darwin/Blue-Rock/default.nix

@@ -1,4 +1,5 @@
-{ pkgs, ... }: {
+{ pkgs, ... }:
+{
   system.stateVersion = 4;
 
   environment = {

modules/hosts/darwin/Blue-Rock/home-gene.liverman.nix

@@ -1,6 +1,7 @@
-{ username, ... }: {
+{ username, ... }:
+{
   home.stateVersion = "23.11";
-    
+
   programs = {
     go = {
       enable = true;