tokenTransport now delegates CloseIdleConnections to the underlying
*http.Transport so http.Client.CloseIdleConnections() works through
the wrapper. Three plugin Close() methods updated to unwrap via
HTTPClientTransport before calling CloseIdleConnections.
RoundTrip now short-circuits when caller already set Authorization,
avoiding an unnecessary req.Clone allocation on the pass-through path.
ginuerzh
618cc7fd9c