Investigate and clean up the state atoms

[CmdrDats]

There's a lot of usages of atom watchers and complex paths inside - it feels like we can do a much simpler job here.

In particular, there are two kinds of things we are mixing together: stateful objects (images, panels, frames, etc) which are not serializable and system state (board size, gameplay history) which is. We should tear out all unserializable state into its own locally managed places where possible.