Cal’s history in Game 7 of an NBA playoff series dates back 60 years, to Darrall Imhoff in 1966. No former Cal player has more experience in Game 7 than Jaylen Brown.  The 29-year-old one-and-done Golden Bear will step onto that stage for the ninth time Saturday night when the Boston Celtics host the Philadelphia 76ers in a win-or-go-home game. Brown and the Celtics have prevailed in six of their previous eight Game 7 showdowns. They were forced into another one after their 106-93 loss at Philly on Thursday night. Surprisingly, the former Cal player with the next-most experience in a Game 7 is Charles Johnson, who played in five such outings.  Ex-Bears Phil Chenier and Kevin Johnson excelled in Game 7s and, curiously, Jason Kidd played in just one of them in 158 postseason games over 19 seasons. Brown, of course, was named MVP of both the 2024 Eastern Conference finals and the NBA finals, but neither of those series reached a seventh game.…