Plenty of Iowans are plotting for a very late night (Thursday) — and many of them may end up being absent from their desks at school or work tomorrow (Friday). Theaters from Sioux City to the Quad Cities plan to debut “Harry Potter and the Goblet of Fire” late tonight — technically early tomorrow morning — at one-past midnight. It’s the fourth installment of seven in the series of films about a boy wizard, based on the wildly popular novels. This is the first of the films to be rated P-G-13, due to frightening images and violence. The running time is two-hours-37-minutes, so any Iowans who -do- take in the late-night edition will face what some affectionatly call a Harry Hangover tomorrow.