IA Pages - Commit page

I have the endpoint and some initial basic layout for the page, but there's a lot more work to do, so I'll mark this as WIP and won't tag anyone just yet.
if we're only going to use the last one, these probably don't need to be arrays.

If we decide in the future to do so, I would much rather go the object route and have lists of objects rather than arrays by field name. The IA object would know what to do with its fields rather than have decode_json littered throughout the code (for example).