LAS VEGAS — Pete Rose wasn’t in the mood to say much Monday, understandable after Commissioner Rob Manfred slammed the door shut on what almost surely will be his last chance at getting back into baseball.It was, however, still a work day. So Rose dutifully sat at a folding table outside the Mandalay Bay casino, pulled out a bag of assorted pens and quickly got down to the business at hand.He signed a black bat, on special this day for just $299. A few fans wandered in, drawn by the two young men in Pete Rose …