🚀 use local flake inputs for registry

modules/config/nix.nix

@@ -1,6 +1,7 @@
 { config
 , lib
 , pkgs
+, inputs
 , ...
 }:
 
@@ -34,6 +35,17 @@ in
       dates = [ "weekly" ];
     };
 
+    registry = {
+      master-upstream.to = {
+        type = "github";
+        owner = "nixos";
+        repo = "nixpkgs";
+      };
+      master.flake = inputs.master;
+      nixpkgs.flake = inputs.nixpkgs;
+      stable.flake = inputs.stable;
+    };
+
     settings = {
       substituters = [
         "https://cache.nixos.org/"