Revert "Remove unused lockscreen module"

This reverts commit 42b6cf8c4a.

modules/lockscreen/default.nix

@@ -0,0 +1,14 @@
+{ pkgs, ... }:
+
+{
+  # enable lockscreen
+  programs.xss-lock = {
+    enable = true;
+    lockerCommand = "${pkgs.i3lock}/bin/i3lock -c 000000";
+  };
+
+  environment.systemPackages = with pkgs; [
+    i3lock
+  ];
+}
+

systems/staubfinger/default.nix

@@ -7,6 +7,7 @@
     "${custom.inputs.self}/hardware/bluetooth"
     (import "${custom.inputs.self}/modules/desktop" { inherit custom; })
     (import "${custom.inputs.self}/modules/docker" { inherit custom; })
+    "${custom.inputs.self}/modules/lockscreen"
     (import "${custom.inputs.self}/modules/restic-client-desktop" { inherit custom; })
     "${custom.inputs.self}/modules/tmux"
   ];