The Iowa Senate Democrat is making healthcare the centerpiece of his Senate campaign, pinning rising premiums and rural hospital closures directly on Republican Ashley Hinson. State Sen. Zach Wahls on Monday released a sweeping healthcare agenda—the fourth installment of his “Iowans Over Insiders” platform—that targets prescription drug costs, rural hospital closures, and Iowa’s worsening cancer crisis, while going after Rep. Ashley Hinson’s vot…