Streaming PostgreSQL COPY helpers backed directly by pgjdbc's CopyManager.

COPY runs on a real java.sql.Connection. The caller owns that connection and
must keep it open for the complete COPY operation.

Allow using PostgreSQL from Clojure as effortlessly as possible by reading connection parameter defaults from
PostgreSQL environment variables PGDATABASE, PGHOST, PGPORT, PGUSER and by reading password from ~/.pgpass if available.

PostgreSQL LISTEN/NOTIFY helpers backed directly by pgjdbc.

Use a dedicated open connection for listening. pgjdbc surfaces notifications
only when a query is issued or get-notifications is called. A blocking poll
prevents other statements from using that connection until the poll returns.

Logic for matching passwords ~/.pgpass passwords to db specs.

Hikari based connection pool

Resolve pgjdbc service definitions into psql-clj database specs.

Extend next.jdbc's SettableParameter and ReadableColumn protocols so that
PGobject (json/jsonb/enum), SQL arrays and inet values move between Clojure
data and PostgreSQL without manual wrapping.

The map->parameter / vec->parameter / num->parameter multimethods are the
extension seam: companion artifacts (e.g. psql-clj-gis) add methods for their
own SQL types without this namespace depending on them.