REDB inside, part 1 — the 13 tables the whole engine runs on (with the actual SQL, and why it's not EAV)

A couple of weeks ago I published the redb.Core intro post — what RedBase is at the API level, why I wrote it, what production looks like, the LINQ surface, what generated SQL looks like for nested dictionary lookups. If you haven't read it, start there — it's the wide-angle shot. This post starts a new series — "REDB inside" — that drills down into the engine. One article per layer: Part 1 (this post) — the database schema. 13 tables, what each one does, why the design is what it is, and the SQ