LATE on an ink-black night in June in the Lebanese hill town of Zahle, a teenage boy sidled up to two travelers as they strolled along the bank of a river. In French-inflected English, he asked an urgent question: ''Have you seen the new Harry Potter book?'' Despite receiving a negative reply, he pressed on, ''Have you heard what happens in it?'' When the answer again was ''no,'' he sighed in vexation. He had read the five other Potter books many times, he explained - both in French and in English, which ''takes longer, but it's better, because it's her words.'' ''Her,'' even to a boy growing up in the Bekaa, meant She-Who-Must-Be-Read: J. K. Rowling, author of the cliffhanger chronicles of the young British wizard Harry Potter and his pals, Hermione Granger and Ron Weasley, from the Hogwarts School of Witchcraft and Wizardry.
