WILMINGTON, Del. — A federal bankruptcy judge in Delaware has approved the Tribune Co.'s sale of the Chicago Cubs. The judge on Thursday authorized Tribune to enter into transactions to sell the team to the family of billionaire Joe Ricketts, founder of TD Ameritrade. The family agreed to buy a 95 percent stake in the team and its Wrigley Field home for $845 million. The deal also needs approval from Major League Baseball. The Tribune plan calls for a separate bankruptcy filing by Chicago National League Ball Club, an affiliate not involved in the company's Chapter 11 case.