This draft implements a rough version of one CXZ rule (primary contribution) and creates an implied marker for it in the indexed version of the record. The stored (in pg) version does not have this implied marker. The (possibly broken out) agent-record where the actual change was made, however, has a "changed agent" marker both in the stored and indexed versions (uggh inconsistent).

It's black magic and sacrificed cats all the way, and there are some side effects of all this:

1. ChangeNotes have to go under mainEntity, and cannot sit (where they perhaps should) in metadata (@graph,0). Because otherwise we cannot (without rebuilding the world) bring them with us when embellishing, which we must.

2. TechnicalNotes and everything they contain must be part of the "card" or "search-card"-definition, because all of the data in these notes must be kept when embellishing, or else we won't have the necessary info from which to imply second order markers. This may have bad knock on-effects, such as for example these notes possibly showing up in the GUI (or otherwise requiring more dead cats to filter them out). For the moment being this was avoided by temporarily hacking the embellish-process, but that won't be good enough in the real world.

Also, this (if/when all the rules are implemented) obviously also only delivers ~1/3 of the CXZ-feature, as the actual stream this is supposed to result in, and all handling of the actual notifications aren't here, and will have to be built in the front end instead.

I consider all this a Very Bad Idea (tm), but there it is.