deploy: add build and deploy script as flake app

scripts/deploy.nix

@@ -0,0 +1,34 @@
+# Copyright (c) 2019-2022, see AUTHORS. Licensed under MIT License, see LICENSE.
+
+{ nixpkgs, system }:
+
+let
+  pkgs = nixpkgs.legacyPackages.${system};
+
+  runtimePackages = with pkgs; [
+    coreutils
+    git
+    gnugrep
+    gnused
+    gnutar
+    gzip
+    jq
+    nix
+    openssh
+    rsync
+  ];
+in
+
+pkgs.runCommand
+  "deploy"
+{
+  preferLocalBuild = true;
+  allowSubstitutes = false;
+}
+  ''
+    install -D -m755  ${./deploy.sh} $out
+
+    substituteInPlace $out \
+      --subst-var-by bash "${pkgs.bash}" \
+      --subst-var-by path "${pkgs.lib.makeBinPath runtimePackages}"
+  ''