You don’t have to step outside into that muggy weather to know what season it is. All you have to do is turn on the TV any afternoon and watch the parade of half-naked nubiles and pec-monkeys as the soaps go through their summer ritual of rejuvenation. It’s a time-honored tradition: Each year, in an attempt to hook all those vacationing students lolling around the house, the daytime serials move the youngest part of the cast onto front-burner stories. That means the skin quotient goes way up, while the acting-quality index dips. Ah, summer, when all the soaps are young and restless.