Meltano with Airflow fails: sqlite database file doesn't exist, do you need to create the database with airflow db init

## What happened

After upgrading to Meltano 2.0, running Airflow failed with an error saying the sqlite database file didn't exist and asking whether to run `airflow db init`. The reporter had Airflow 1.10 configured and then tried 2.1, but the metadata DB setup kept breaking. A maintainer walked through the migration: Airflow 2.x replaced the old `AIRFLOW__CORE__SQL_ALCHEMY_CONN` with `AIRFLOW__DATABASE__SQL_ALCHEMY_CONN`, and the postgres connection scheme had to be `postgresql://` (with the l), not `postgres://`. The working setup was Airflow 2.3.2 with a fresh metadata database, the new env var names, and the `postgresql://` scheme. The reporter confirmed this combination worked and thanked the maintainers.

## The fix that worked

Meltano 2.0 changed how Airflow config is passed through, and Airflow 2.x renamed the database env vars, so the old settings silently stopped pointing at a real metadata DB. Fix: use Airflow 2.3.2, set `AIRFLOW__DATABASE__SQL_ALCHEMY_CONN` (the 2.x name) with a fresh metadata database, and use the `postgresql://` connection scheme with the l, since `postgres://` is no longer accepted. Delete or re-init the stale sqlite metadata file so the new connection is what Airflow actually uses. The reporter used this exact combination and confirmed Airflow started cleanly.