WASHINGTON — President Joe Biden on Monday proposed major changes for the U.S. Supreme Court: an enforceable code of ethics, term limits for justices and a constitutional amendment that would limit the justices’ recent decision on presidential immunity. There’s almost no chance of the proposal passing a closely divided Congress with Election Day looming, but the ideas could still spark conversation with public confidence in the court hitting an all-time low amid ethical revelations about some justices. It also comes against the backdrop of a contentious presidential election and growing Democr…