There's a new company at the center of the intensifying battle between Elon Musk and Sam Altman: Apple.Musk and Altman, who helped start OpenAI a decade ago with a group of other co-founders, had a public falling out that led to a legal fight last year, with Musk accusing Altman of breach of contract for abandoning the artificial intelligence company's founding mission.The back-and-forth war of words and lawsuits took another dramatic turn on Monday, when Musk threatened Apple with "immediate" legal action ...