A yard sign opposing a planned data center is displayed along Route 54 in Mount Carmel Township Northumberland County. | Image: Getty Images This is The Stepback, a weekly newsletter breaking down one essential story from the tech world. For more on the data center buildout, follow Emma Roth. The Stepback arrives in our subscribers' inboxes on Sunday at 8AM ET. Opt in for The Stepback here. How it started Years before the AI boom threatened local power grids, a small group of protesters set…