Add multi-host configuration

based loosely on https://github.com/tom-on-the-internet/system-configuration

hosts/configuration.nix

@@ -0,0 +1,39 @@
+{ config, pkgs, user, inputs, ... }:
+
+{
+  # Automatically delete generations older than a week
+  nix.gc = {
+    automatic = true;
+    options = "--delete-generations 8d";
+  };
+
+  networking.networkmanager.enable = true;
+
+  time.timeZone = "America/Los_Angeles";
+
+  users.users.${user} = {
+    isNormalUser = true;
+    extraGroups = [ "wheel" "audio" "video" "optical" "storage" ];
+    initialPassword = "password";
+  };
+
+  nixpkgs.config.allowUnfree = true;
+
+  nix = {
+    package = pkgs.nixVersions.stable; # flakes
+    extraOptions = "experimental-features = nix-command flakes";
+  };
+
+  environment.systemPackages = with pkgs; [
+    rustc
+    cargo
+  ];
+
+  # 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 = "22.05"; # Did you read the comment?
+}