add new external flake to provide helper functions

modules/hosts/takamaki/home/zsh.nix

@@ -1,7 +1,8 @@
 { inputs, self, ... }: {
   flake.homeModules.takamaki = { config, pkgs, ... }: {
     programs.zsh.shellAliases = {
-      apply-config = "zsh -c 'cd /home/grey/flake; git add .; home-manager switch --flake .#takamaki -b bak'";
+      apply-config = "zsh -c 'cd ${config.info.rootPath}; git add .; home-manager switch --flake .#takamaki -b bak'";
+      update-config = "zsh -c 'cd ${config.info.rootPath}; git add .; nix flake update; home-manager switch --flake .#takamaki -b bak'";
     };
   };
 }