- Clean up submittedNamedStatements on error in _handleErrorMessage to
  prevent stale entries from blocking future re-preparation of the same
  named statement after a parse failure
- Guard _pulsePipelinedQueryQueue against non-queryable connections
- Fix cancel() and readTimeout for sent queries: removing an already-sent
  query from _sentQueryQueue corrupts the pipeline response mapping since
  the server will still respond to it; no-op the callback instead
- Add bench-pipelining.js comparing serial vs pipelined throughput

Gate _sentQueryQueue activation on readyForQuery=true inside
_pulsePipelinedQueryQueue (and remove the redundant promotion block
from _handleReadyForQuery) to eliminate the microtask/macrotask race
where the next query could be activated as _activeQuery before the
error's ReadyForQuery arrived, causing that RFQ to be handled by the
wrong query.

Also adds the error-listener fix for the query_timeout integration test
so the expected stream-destroy doesn't leak as an unhandled 'error'.

- New features/pipelining.mdx documenting the opt-in flag
- Client and Pool API reference updated
- Pool accepts `pipelining: true` and sets it on every client it creates

The native client end() was immediately terminating the connection,
causing "Connection terminated" errors for queries still in the pipeline.
Now waits for the drain event before closing when pipelining is active.

Also fix pipeline mode to use sendQueryParams instead of sendQuery,
since PostgreSQL rejects simple query protocol in pipeline mode.

…nd skip JS-only tests

handleError in native/query.js crashes when this.native is undefined
(e.g. query_timeout fires before pipeline callback sets it).

Skip named statement cleanup and query_timeout tests for native client
since those features rely on JS-specific internals.