Underage sexpot, junkie, porn star, stripper, spy: No, that’s not a rap sheet — it’s a list of roles Heather Graham has indelibly brought to life in her 30 years as an actor. And with her latest role on Showtime’s edgy hit “Californication,” she takes another sexy star turn: as Julia, a former lover of Hank Moody’s (David Duchovny) and a white-hot mom.