WASHINGTON — Donald Trump’s closest campaign advisers, top government officials and even his family were dismantling his false claims of 2020 election fraud ahead of Jan. 6, but the defeated president was becoming “detached from reality” and clinging to outlandish theories to stay in power, the committee investigating the Capitol attack was told Monday. On Election night itself, Trump was “growing increasingly unhappy” and refusing to accept the results as they came in, former campaign manager Bill Stepien said in testimony played before the House panel. Son-in-law Jared Kushner tried to steer Trump away from attorney Rudy Giuliani and his far-flung theories of voter fraud that advisers believed were not true.