We'll keep the door open for side-by-side support of Postgres in
the background, but due to SQLite's type system quirks we cannot
use the same DDL for both databases, so we would have to maintain
two sets of DDL (schema init and schema migration scripts) at once.
Interested future contributors can shoulder this maintenance burden
if they so choose.
This is in preparation for a transition to SQLite. SQLite does have
a similar concept called "attached databases", but it's kind of a
pain to deal with if you're casually browsing a database from the
`sqlite3` CLI so we'll just use some slightly uglier explicitly
namespaced table name identifiers instead.