Audit and validate the PostgreSQL shared driver

[jamessewell]

If you're a PostgreSQL expert, we'd love your help reviewing our shared Postgres driver.

What this driver does

The shared PostgreSQL driver (backends/shared/postgres/) powers two backends: ParadeDB and PostgreSQL FTS. Each registers separately with different default ports and env vars, but they share this single driver implementation.

It implements the Driver interface using pgxpool (jackc/pgx v5):

• Exec — splits multi-statement SQL with pgsplit and executes each statement sequentially
• Query — runs a query via the pool and counts returned rows as the hit count
• Insert — bulk loads rows using PostgreSQL COPY protocol (pgx.CopyFrom)
• Update — upserts using INSERT ... ON CONFLICT DO UPDATE with dynamically built parameterized queries
• CaptureConfig — reads pg_settings GUCs and runs version queries, with extensible extra GUCs and custom queries for specializations (e.g. ParadeDB version info)

Connection pooling is configured with MaxConns=1, MinConns=1, 30m lifetime, 5m idle timeout.