Summer entertainment options do not get more counterintuitive than the Broadway adaptation of George Orwell’s “1984” that opened at the Hudson Theatre on Thursday, just as beach season swings into high gear. In truth, to call this almost unrelievedly grim production entertainment may be misleading. If you’re in the mood for a meal of pure spinach, to use a now-outmoded food metaphor, this 100-minute immersion in one man’s bleak odyssey through a brutally oppressive culture certainly fits the ticket. The adaptation, written and directed by Robert Icke and Duncan Macmillan, comes with a London pedigree and features a skilled cast led by Tom Sturridge as…