feat: adds user for remote building

modules/services/remote-build.nix

@@ -0,0 +1,55 @@
+{
+  config,
+  pkgs,
+  username,
+  ...
+}:
+{
+  users.users.remotebuild = {
+    isNormalUser = true;
+    createHome = false;
+    group = "remotebuild";
+    openssh.authorizedKeys.keys = config.users.users.${username}.openssh.authorizedKeys.keys ++ [
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAINKI2KQn97mykFLIaMUWMftA1txJec9qW56hAMj5/MhE liv@dandelion
+"
+    ];
+  };
+
+  users.groups.remotebuild = { };
+
+  nix = {
+    nrBuildUsers = 64;
+    settings = {
+      trusted-users = [ "remotebuild" ];
+
+      min-free = 10 * 1024 * 1024;
+      max-free = 200 * 1024 * 1024;
+
+      max-jobs = "auto";
+      cores = 0;
+    };
+  };
+
+  systemd.services.nix-daemon.serviceConfig = {
+    MemoryAccounting = true;
+    MemoryMax = "90%";
+    OOMScoreAdjust = 500;
+  };
+
+  # add to clients:
+  # nix.distributedBuilds = true;
+  # nix.settings.builders-use-substitutes = true;
+  # nix.buildMachines = [
+  #   {
+  #     hostName = "violet";
+  #     sshUser = "remotebuild";
+  #     sshKey = "/home/liv/.ssh/id_ed25519"; # Make sure to give a key that works for this user.
+  #     system = pkgs.stdenv.hostPlatform.system;
+  #     supportedFeatures = [
+  #       "nixos-test"
+  #       "big-parallel"
+  #       "kvm"
+  #     ];
+  #   }
+  # ];
+}