fix(pgwire): improve libpq and ActiveRecord compatibility - #184

Summary

• advertise a libpq-parseable PostgreSQL-compatible server version across startup and session settings
• implement consistent RESET behavior for pgwire parameters
• add ActiveRecord catalog reflection support for pg_range, pg_attrdef, and pg_collation
• return PostgreSQL text-array syntax from current_schemas(...)
• support PostgreSQL metadata functions and correct default, nullability, type, and collation reflection
• correct residual outer-join predicates, qualified post-join filters, and computed catalog projections

Validation

• cargo nextest run -p nodedb --lib --no-fail-fast
• cargo nextest run -p nodedb-sql
• cargo nextest run -p nodedb-query
• cargo nextest run -p nodedb-physical
• cargo nextest run -p nodedb --test pg_catalog_reflection
• cargo clippy -p nodedb -p nodedb-sql -p nodedb-query -p nodedb-physical --all-targets -- -D warnings
• cargo fmt --all --check