Tom Brady has returned little of his riches to community charities, according to a Globe review of tax records as well as interviews with players, team executives, and officials at nearly 25 of the city's leading nonprofit institutions. Those familiar with Brady said the star has yet to decide how best to make a charitable impact in the community. Brady, who earned $13 million over his first four years with the Patriots, signed a six-year extension in May worth $60 million.