The search prototype, at this point, is just a whole lot of JavaScript.
After all of that JavaScript has been loaded, it'll replace the existing search bar (that looks nothing at all like the new search).
This, of course, take a little while, and there's a very noticeable FOUC once this happens.

To counteract this, we should pre-render a functional search widget on the backend.
It doesn't need to have all the features of the JavaScript version (it can't...), but it has to look the same.
Possibly simply provide an input box with freeform "keywords" input, and a regular dropdown widget?

Figure out what steps/work are involved to make this work, and provide more details, in this or other tickets.