Workers who were employed by the city of Chicago before 2003 are guaranteed health-care coverage under the Illinois Constitution at levels that were set more than 30 years ago, a state appeals panel ruled Thursday.The decision from the 1st District Appellate Court is a mixed victory for the city and the retirees who have been fighting over whether the municipal government must subsidize its workforce health care since 1983.At the end of his 24-page opinion, Justice John B. Simon wrote that the panel’s ruling &ldquo …