WASHINGTON - One year and one week ago, Barack Obama stood on the steps of the Capitol to give his inaugural address. His challenge then was to re-inspire Americans’ confidence in themselves. Tonight, inside that building, his challenge is to re-inspire their confidence in him. A year into his presidency, we are less sure than ever who he really is — what he believes, what’s in his heart and gut — and whether he has what it takes to be president. The reason has less to do with his famously cool persona — though that is part of it — than with the decisions he made after those early efforts to