If you watched the new “American Idol” on ABC on March 25, you got a glimpse of the Kehoe Iron Works at Trustee’s Garden, where that episode of Idol was filmed this past October. The Kehoe Iron Works is not only one of the most far-ranging and ambitious historic and greenspace renovations in Savannah history, it’s an instant game-changer for local performing arts, culture and quality of life. The public will have its first chance to experience the new space in person at the all-day festival finale of the Savannah Music Festival on April 14.