In this change, we cache the zones table as part of the JS build process. This keeps the database as our source of truth, while aggressively caching the data at deploy time.
See the new README for some rationale!
I tested this by pulling up dev Honeycomb, and observing that we no longer run db queries to `zones` in the new traces for the wardrobe page. (It's a good thing we did it this way, because I noticed some code in the server that was still loading the zone anyway, and fixed it here!)
I guess if you return a reference to an object that doesn't exist, it registers as null; and you need to provide the `true` here to declare that it _is_ real and should be treated as an _insufficiently_ defined object?
