This could be a cautionary tale. Specifically, for the Super Bowl champion Seahawks. Last month, the NBA board of governors approved a sale of the Portland Trail Blazers to a group led by Texas billionaire Tom Dundon. In the weeks since, Portland made its first playoff appearance since 2021, upsetting the Phoenix Suns in a play-in stunner. Powered by first-time All-Star Deni Avdija and former lottery picks Shaedon Sharpe, Scoot Henderson and Donovan Clingan, the Blazers — who fell to the favored San Antonio Spurs in five games — could contend for seasons to come. It should smell downright rosy in Rip City. But Dundon’s first impression has been frugal to a fault. And Paul Allen’s estate — which will soon sell the Seahawks — handed him the reins.…