The defending World Series champion SF Giants have an awfully diverse promotional schedule lined up for 2013 ;  along with Bruce Lee Tribute Night, Law Enforcement Appreciation Night and Star Wars Day, Metallica will be the guests of honor on May 3.   Though the special-edition Giants/Metallica cap isn’t nearly as exciting as say, a Cliff Burton Bobblehead, my curiosity is piqued by the club promising, “Metallica entertainment features throughout the game.”   That could mean any number of things, but hopefully the Giants will manage to show some classic archival footage over the AT&T Park jumbotron.