pool.end() against PgBouncer transaction-mode never drained, so disconnect
blocked until the CLI's 10s force-exit fired and process.exit()'d mid-write,
truncating stdout (e.g. #1959's relational query returned empty). Add a
gbrain-owned endPoolBounded(pool): Promise.race of pool.end({timeout}) against
a hard timer, so teardown is bounded regardless of what postgres.js does and is
testable. connection-manager ends its direct + read pools concurrently so the
per-pool bounds don't stack. PGLite disconnect is unaffected.
