By Michael CohenI was sitting in a restaurant and about to sing “Happy Birthday” for a relative when a message came through. I heard my brother’s voice, quivering. He told me not to worry, that he was okay — I could barely hear what he was saying because the line was muffled. I rang him straight back.Minutes earlier, he had been watching the ceremonial Chanukah getting lit as waves crashed along Bondi Beach. His children had been playing on infl…