By Daniel Chavkin San Francisco will enter the offseason with Purdy and Trey Lance both on the roster. Since Brock Purdy has taken over as the starting quarterback of the 49ers, the team is an undefeated 6–0, with seven wins when including the game Purdy replaced an injured Jimmy Garoppolo. In those seven games, Purdy has 16 touchdowns to just three interceptions, with a completion percentage over 60% in each game. Entering the offseason, San Francisco will once again have a decision to make at quarterback, as Garoppolo hits free agency and Trey Lance returns from injury. However, the decision…