feat(nix): add style tooling

src/dotfiles/apps.nix

@@ -0,0 +1,28 @@
+{
+  inputs,
+  lib,
+  formatter,
+  system,
+}:
+let
+  pkgs = inputs.nixpkgs.legacyPackages.${system};
+in
+{
+  fix = {
+    type = "app";
+    program = lib.getExe (pkgs.writeShellApplication {
+      name = "fix";
+      runtimeInputs = [
+        formatter.config.build.wrapper
+        pkgs.statix
+        pkgs.deadnix
+      ];
+      text = ''
+        treefmt
+        statix fix .
+        deadnix --edit --exclude configs/nixos/hosts/*/hardware-configuration.nix -- .
+        treefmt
+      '';
+    });
+  };
+}

src/dotfiles/default.nix

@@ -3,6 +3,7 @@
   inputs,
   self,
   root,
+  system,
 }:
 let
   util = import ./util.nix { inherit lib; };
@@ -38,8 +39,23 @@ let
       ;
     registry = registry.collected;
   };
+
+  formatter = import ./formatter.nix {
+    inherit inputs system;
+  };
 in
 {
+  formatter.${system} = formatter.config.build.wrapper;
+
+  apps.${system} = import ./apps.nix {
+    inherit
+      inputs
+      lib
+      formatter
+      system
+      ;
+  };
+
   nixosConfigurations = import ./hosts.nix {
     inherit
       inputs

src/dotfiles/formatter.nix

@@ -0,0 +1,10 @@
+{ inputs, system }:
+inputs.treefmt-nix.lib.evalModule inputs.nixpkgs.legacyPackages.${system} {
+  projectRootFile = "flake.nix";
+
+  programs.nixfmt.enable = true;
+
+  settings.formatter.nixfmt.excludes = [
+    "configs/nixos/hosts/*/hardware-configuration.nix"
+  ];
+}