SQLDialect interface abstracts SQLite vs PostgreSQL SQL differences:
- JSON ops (json_extract vs ->>, json_each vs jsonb_array_elements)
- Date formatting (strftime vs to_char)
- Schema introspection (PRAGMA vs information_schema)
- ID generation (randomblob vs gen_random_bytes)
Adds PostgresDBConnect via pgx driver and DataDSN/AuxDSN config fields
for connecting Base to Neon serverless PostgreSQL instead of SQLite.
