Jennifer Maas TV Business WriterSPOILER ALERT: Do not read if you have not yet watched “A Dream of a Thousand Cats”/”Calliope,” the surprise 11th episode of “The Sandman” Season 1.Netflix’s “The Sandman” was always meant to have 11 episodes in its first season — you just didn’t know it until the special final installment, a two-part animated and live-action story titled “A Dream of a Thousand Cats”/”Calliope,” dropped Friday.Or, if you’re a diehard fan who has been following every piece of “Sandman” news since the TV adaptation of Neil Gaiman’s beloved graphic novels was first ordered to series in July 2019, you might have been slightly gaslit into not remembering that there were 11 episodes when the 10-episode season launched two weeks ago. “There may have been hints earlier.