Step inside the co-op at University of Texas at Austin these days, and you can feel the buzz of a winning season. The jerseys of quarterbacks Quinn Ewers and Arch Manning hang from wall racks, too in demand to dangle there for long. The members of the bald mannequin family by the front door show off their excitement about joining the Southeastern Conference. They sport SEC T-shirts and other burnt orange gear—even their plastic dog wears a Longhorns-branded harness. Beside them, a sign advertises a new “Celebrate the Win” T-shirt, a tribute to UT’s recent triumph over the University of Michigan—a souvenir to ensure the sweetness of victory lasts a little longer.As the world of Texas college football spins this fall, the collegiate shops across…