SEATTLE — Jay Harbaugh, the son of Chargers coach Jim Harbaugh, is expected to join the Seahawks’ coaching staff as special-teams coordinator, a league source confirmed to The Seattle Times. SI.com and 247sports.com initially reported the move Monday. Jay Harbaugh and new Seahawks coach Mike Macdonald have twice coached together — in 2014 with the Ravens (Macdonald as a defensive intern and Harbaugh as offensive quality control coach) and in 2021 when Macdonald was the defensive coordinator at Michigan and Harbaugh the tight-ends coach and special teams coordinator. Harbaugh was the safeties c…