Adds a migration for an initial schema. Adds sqlx-cli to the flake
so that I use those migrations easily.
adds an UNTESTED "direct" interface, which should make writing ingestors
easier, and be very easy for spoor lexicons. It will probably also be
easy for other lexicons if they can fit into the Activity -> Session ->
Content interface.
Adds errors because I needed errors.
Since this is a library, and as you can see there are no tests, that
means that everything is *untested* which is fine because I want a MVP
not a stable app. For now.
Moves file contents out of ./rust since I'm planning to go with rust for
the backend and the lexicons will be used for codegen soon anyways.
I also added extra files that have been in the works that I have been
accidentally sprinkling into main.rs already. God forbid I need to
cherry-pick anything from so far back in the history.
It will make git blame ugly though.
