Put the other menus in the top bar

The bar hid them behind a switcher and a sheet. It now names every menu that
exists, which is what was asked for; it scrolls sideways when the categories
outgrow the width, and the current one is the only filled item. Without the
script it is simply a row of links, so nothing is lost when JavaScript is off.

.gitignore

@@ -4,3 +4,5 @@ node_modules/
 .dev/
 *.log
 site.env
+# design prototype, never committed to main and never shipped
+/public/prototype/