Tuesday, February 26th 4:18 PM   The observation deck at the top of Pyramid Plaza was empty, save for one woman. No one else wanted to be in there right now, except for the people who were paid to be there.    Around twenty minutes ago, the young woman had entered the observation deck. There wasn't much odd about here - sweatshirts, jeans, sneakers, short and somewhat untamed hair. She stood before the windows of the deck for about five minutes, not moving. And then she'd started pressing he