Migrate internal databases to sqlite

[wizzomafizzo]

Currently the games.db and tapto.db files are KV stores which are pretty inflexible, can blow out in size from mass removals (like a re-index), and aren't viewable from any other standards apps.

I want to migrate both to sqlite databases. Likely using the modernc library (no CGo)

During the migration, I also want to rename games.db to media.db and tapto.db to user.db