move common and desktop to modules dir

modules/common.nix

@@ -0,0 +1,84 @@
+{
+  lib,
+  pkgs,
+  config,
+  nixpkgs,
+  ragenix,
+  ...
+}: {
+  environment = {
+    systemPackages = with pkgs; let
+      inherit (pkgs.stdenv.hostPlatform) system;
+    in [
+      ragenix.packages.${system}.default
+      neovim
+      git
+      curl
+    ];
+
+    variables = {
+      EDITOR = lib.getExe pkgs.neovim;
+    };
+  };
+
+  age.secrets = {
+    tailscaleKey.file = ../secrets/tailscaleKey.age;
+  };
+
+  programs = {
+    ssh.startAgent = true;
+
+    direnv.enable = true;
+
+    command-not-found.enable = false;
+    nix-index = {
+      enable = true;
+      enableFishIntegration = true;
+    };
+  };
+
+  services = {
+    openssh = {
+      enable = true;
+      openFirewall = lib.mkDefault false;
+    };
+
+    tailscale = {
+      enable = true;
+      useRoutingFeatures = "both";
+      extraUpFlags = ["--ssh"];
+      authKeyFile = config.age.secrets.tailscaleKey.path;
+    };
+  };
+
+  nixpkgs.config.allowUnfree = true;
+
+  nix = {
+    gc = {
+      automatic = true;
+      dates = "weekly";
+      options = "-d";
+    };
+
+    settings = {
+      auto-optimise-store = true;
+      experimental-features = ["nix-command" "flakes"];
+      trusted-users = ["root" "@wheel"];
+    };
+  };
+
+  nix.registry = let
+    nixpkgsRegistry.flake = nixpkgs;
+  in {
+    nixpkgs = nixpkgsRegistry;
+    n = nixpkgsRegistry;
+  };
+
+  # This value determines the NixOS release from which the default
+  # settings for stateful data, like file locations and database versions
+  # on your system were taken. It‘s perfectly fine and recommended to leave
+  # this value at the release version of the first install of this system.
+  # Before changing this value read the documentation for this option
+  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
+  system.stateVersion = lib.mkDefault "23.11"; # Did you read the comment?
+}