Change hostname to chromatic-aberration, enable SSH

Since it's a Chromebox and that name sounds vaguely cool I guess

flake.nix

@@ -13,8 +13,7 @@
       pkgs = import nixpkgs { inherit system; };
     in
     {
-      # NOTE: 'nixos' is the default hostname
-      nixosConfigurations.nixos = nixpkgs.lib.nixosSystem {
+      nixosConfigurations.chromatic-aberration = nixpkgs.lib.nixosSystem {
         modules = [ ./configuration.nix ];
       };
       formatter.${system} = pkgs.nixfmt-tree;