Donald Trump’s megalomania will either spell “electoral calamity” for Republicans in the 2024 election or the beginning of American carnage the likes of which the world has never seen, an expert on neoconservatives said Friday. Jacob Heilbrunn, author of “America Last: The Right’s Century-Long Romance with Foreign Dictators,” raised his serious concerns with Salon Friday over the Republicans who have lined up behind a presumptive nominee he warns could dismantle democracy at home and abroad. “The most disturbing thing remains Trump’s enablers — the incense-burners, the bootlickers, the pursuiv…