“IT MAY NOT be good for America, but it’s damn good for CBS,” said Leslie Moonves, the TV network’s then boss, of Donald Trump’s presidential candidacy in 2016. Ratings soared under Mr Trump, and slumped when he left the stage. Now war has people tuning in again. Since Russia invaded Ukraine, cable-news channels’ audience share in America has nearly doubled, to 12%, reckons Inscape, a data firm—heights last recorded when the…