Kemba Walker’s Brookline mansion has sold months after the Boston Celtics traded the All-Star point guard to the Oklahoma City Thunder. The 9,592-square-foot Brookline mansion at 37 Sears Road closed for an undisclosed sum on Oct. 26, according to filings made public this week with the Norfolk County Registry District of the Land Court and in an Instagram post from Newbrook Realty founder Samantha Stumpo, who has now sold the home twice.