install crystal instead of spritely-crystal which breaks raco commands

See merge request sprite...

Also adds some comments for future work / acknowledgements sections.

It only becomes necessary once we hit "how it works"

And, move where we first talk about it.

but there's a major refactor going on

Sometimes you want referenceable exact URIs, and sometimes you want
the magnet URIs they point to.

While I don't have an exact attack in mind, feels like something
that needs to be caught.

This better reflects what the command actually means.

Not that all tests are passing though :)

- can now serve its own magenc store
- set up so that we can add an sqlite store if need be

Which... mostly works!