Who knew the end of the world could be so life-affirming? And who would have guessed that a Stephen King short story adapted by fellow Master of Horror Mike Flanagan would result in the feel-good movie of the year? The challenge with talking about “ The Life of Chuck ” is that it’s a film that should be discovered — the less you know going in, the better. Which made it challenging to market. Is it a drama? A musical? A romance? A coming-of-age story? A movie that does nothing less than ask