home: wm: use 'i3lock' with 'i3'

Rather than use it as the default, set it in the `i3` module.

modules/home/wm/default.nix

@@ -1,4 +1,4 @@
-{ config, lib, pkgs, ... }:
+{ config, lib, ... }:
 let
   mkRelatedOption = description: relatedWMs:
     let
@@ -72,7 +72,6 @@ in
 
       command = mkOption {
         type = types.str;
-        default = "${lib.getExe pkgs.i3lock} -n -c 000000";
         example = "\${lib.getExe pkgs.i3lock} -n -i lock.png";
         description = "Locker command to run";
       };

modules/home/wm/i3/default.nix

@@ -71,6 +71,9 @@ in
       xdotool # Used by 'rofi-rbw', in a mapping
     ];
 
+    # Set `i3lock` as the (default) lock command
+    my.home.wm.screen-lock.command = lib.mkDefault "${lib.getExe pkgs.i3lock} -n -c 000000";
+
     xsession.windowManager.i3 = {
       enable = true;