A taxa `SqlSource`: run a Postgres query and ingest the result into an
in-memory Polars `DataFrame`, exposed as a [`taxa-core`](https://crates.io/crates/taxa-core)
`Source`.
DATE/TIMESTAMP columns decode to `chrono`, NUMERIC to `rust_decimal::Decimal`,
and INT2 to a real `Int16` series.
Part of the [taxa](https://github.com/paradigmxyz/taxa) workspace.
MIT