Show the queue with a before-and-after diff of the response

Problem/Motivation

"A field was added" is not information a person can act on. What they need to see is what the response looks like now and what it would look like after applying — that is the difference between an informed approval and a click.

Proposed resolution

• A queue page listing entries with a filter by kind and by bundle.
• Per entry, a JSON diff of a real response before and after, built against a sample entity of the bundle.
• A removed key marked as breaking and shown differently from an added one — the front end survives the second and not the first.
• The page is usable with a hundred entries, which is what a first scan of a real site produces.

Remaining tasks

Everything.