Once again, we present you with Ed Bark, otherwise known as Uncle Barky: The thrill of victory and, for the first time, the agony of high-def. Wheel of Fortune has both going for it this fall, which makes the show's two longrunning stars just a little camera-shy. Vanna White, who will hit the half-century mark on Feb. 18, isn't ready for those kinds of closeups. Pat Sajak, who turned 60 last Thursday, would just as soon be shot the old-school way. They talked about putting their pores on the line during a recent stop in Dallas to tape three weeks worth of Texas-themed shows that begin rolling out Monday. "No. No, of course I'm not ready for it," White says without batting an eyelash. "It shows every line and wrinkle in your face. Makes you look 20 times older than you are!" But how does she really feel?