When an advertiser pays to have its product appear in a movie, the “cameo” typically runs just a few seconds. An exception is the role played by the Ford Mustang in “A Man and a Woman” (1966).There, the Mustang took center stage in several long sequences. But that starring role is nothing compared to the dominance of the iPhone 13 in “Pavel,” a 48-second faux drama. The phone is onscreen only at the end. But its presence is felt throughout.