Add preview images to the themes menu (#3444)

* Add new script for themes menu

* remove icons from the themes menu

* Make theme titles human readable and add spacing at the end

* Migrate to using a link for the new menu generator

* Retain consistent width

But we still do have movement when filtering the menu down to a
shorter-than-longest name. Should try to stabilize that.

* Update all previews to 2K resolution and same dimensions

* Update script to use first bg file if theme preview file doesn't exist

* Add padding to preview box instead of spaces to theme name

* Consistent formatting/indenting

* Prevent height jump

* Revert padding change and remove background color

---------

Co-authored-by: David Heinemeier Hansson <david@hey.com>

bin/omarchy-menu

@@ -154,12 +154,7 @@ show_style_menu() {
 }
 
 show_theme_menu() {
-  theme=$(menu "Theme" "$(omarchy-theme-list)" "" "$(omarchy-theme-current)")
-  if [[ "$theme" == "CNCLD" || -z "$theme" ]]; then
-    back_to show_style_menu
-  else
-    omarchy-theme-set "$theme"
-  fi
+  omarchy-launch-walker -m menus:omarchythemes --width 800 --minheight 400
 }
 
 show_font_menu() {