Wilson Chapman editorSpoiler Alert: Do not read if you haven’t watched “The Piggyback,” the final episode of “Stranger Things 4,” now streaming on Netflix.Season 4 of “Stranger Things” ends on the show’s most bittersweet note yet, with the crew barely managing to scrape together a (seemingly temporary) victory against main villain Vecna (Jamie Campbell Bower) in their quest to save Hawkins, Ind. from the Upside Down.