feat(scripts): extend nomarchy-welcome into a guided wizard

- Added nomarchy.panelPosition option and state persistence.
- Updated Waybar to respect the panelPosition setting.
- Refactored nomarchy-welcome to use state.json instead of a flag file.
- Added prompts for theme, font, panel position, and starter home.nix generation.
- Updated documentation and roadmap.

core/home/options.nix

@@ -61,6 +61,11 @@
       default = "";
       description = "System wallpaper path.";
     };
+    panelPosition = lib.mkOption {
+      type = lib.types.enum [ "top" "bottom" ];
+      default = "top";
+      description = "Waybar panel position.";
+    };
     hyprland = {
       gaps_in = lib.mkOption {
         type = lib.types.int;