Endings are hard. That’s particularly true for serialized mystery box TV shows, ones where plentiful juicy secrets hook viewers but the answers often fail to satisfy them. Putting a final bow on a story like that is a unique challenge. That’s part of what makes Servant, the Apple TV Plus psychological thriller helmed by M. Night Shyamalan, so interesting. Whereas many of these shows seem like they’re making it up as they go, Servant had a specific ending in mind. As Shyamalan told me…