fix(distro): fix /etc/nixos ownership, theme discovery, and CLI wrappers

- installer: set recursive ownership of /etc/nixos to main user post-install
- themes: fix NOMARCHY_PATH and discovery logic for Lua theme menu
- scripts: update CLI wrappers (font, theme, wallpaper) to use Walker menus
- core: remove obsolete NOMARCHY_PATH and cleanup dead code
- features: add pkgs.lua for Walker and remove obsolete switcher.nix
- docs: update ROADMAP.md, SCRIPTS.md and STRUCTURE.md

features/apps/walker.nix

@@ -1,6 +1,8 @@
 { config, pkgs, lib, ... }:
 
 {
+  home.packages = [ pkgs.lua ];
+
   programs.walker = {
     enable = lib.mkDefault true;
     runAsService = lib.mkDefault true;