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

core/system/scripts-derivation.nix

@@ -56,7 +56,7 @@ pkgs.stdenv.mkDerivation {
       if [ -f "$file" ]; then
         wrapProgram "$file" \
           --prefix PATH : "$deps" \
-          --set NOMARCHY_PATH "/etc/nixos/nomarchy"
+          --set NOMARCHY_PATH "/etc/nixos"
       fi
     done
   '';