feat(nix): add registry entry to self

flake.nix

@@ -142,7 +142,7 @@
           lib.nixosSystem {
             inherit pkgs system lib;
             specialArgs = {
-              inherit inputs;
+              inherit inputs self;
             };
             modules = defaultModules ++ [ path ];
           })

modules/programs/nix.nix

@@ -1,6 +1,7 @@
 { config
 , lib
 , inputs
+, self
 , ...
 }:
 
@@ -22,6 +23,8 @@ in
   };
 
   config.nix = {
+    extraOptions = "experimental-features = nix-command flakes";
+
     gc = {
       automatic = cfg.gc.enable;
       options = "--max-freed ${cfg.gc.minimumFreedGB} --delete-older-than 14d";
@@ -42,6 +45,7 @@ in
       master.flake = inputs.master;
       nixpkgs.flake = inputs.nixpkgs;
       stable.flake = inputs.stable;
+      dotfiles.flake = self;
     };
 
     settings = {