Further file arrangement

system/darwin/default.nix

@@ -4,8 +4,27 @@
   imports = [
     ../../modules/homebrew.nix
     nix-homebrew.darwinModules.nix-homebrew
+    ../../modules/tailscale.nix
   ];
 
+  # Nix configuration
+  nix.settings.experimental-features = "nix-command flakes";
+  nix.settings.substituters = [
+    "https://cache.nixos.org/"
+    "https://nix-community.cachix.org"
+    "https://devenv.cachix.org"
+  ];
+  nix.settings.trusted-public-keys = [
+    "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+    "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+    "devenv.cachix.org-1:w1cLUi8dv3hnoSPGAuibQv+f9TZLr6cv/Hm9XgU50cw="
+  ];
+  
+  # System configuration
+  system.stateVersion = 6;
+  nixpkgs.hostPlatform = "aarch64-darwin";
+  programs.zsh.enable = true;
+
   # Set primary user for system preferences
   system.primaryUser = "yanlin";