SAN FRANCISCO — Veronica Burton checked out with 7:29 left in the third quarter, huffing for air a bit and visibly miffed following a rough sequence. The Golden State point guard — who missed a wide-open layup and chased it with a 27-foot stepback 3 that landed short — headed through the tunnel and out of sight. Anyone who knows Burton could imagine her internal chastisement. But the leader of these Valkyries, also predictably, returned to the bench, put on her jacket and locked in on the action