Apple paid $100M to put a U2 album on 500 million phones, then spent six days building a special tool to help people delete it. That removal page is the strangest product Apple ever shipped. Its only function was undoing another Apple product. But the backlash taught them something worth far more than $100M. In 2014, your iTunes library was a possession. You built it purchase by purchase, 99 cents at a time, over a decade. When an album appeared there uninvited, it registered like a…