The future of Saints Medical Center is brighter after its board of trustees agreed to be acquired by Steward Health Care LLC in a $98 million deal that immediately infuses cash and confidence into the financially ailing hospital. Saints' 1,300 employees are safe in their jobs, officials said, and the hospital will have access to $5 million in cash to modernize its facility and equipment while paying off $60 million in debt and pension liabilities. The hospital, founded more than a century ago to care for mill workers, will retain its Catholic mission. "Saints will benefit greatly from its association with Steward," board of trustees Chairman Victor Poirier said. "I'm very happy for the employees because free-standing community hospitals, like Saints, will find it more difficult to survive without an affiliation with a larger organization. This was in the best interest of Saints. Saints' future is bright today." But healthcare analysts and others monitoring Steward's march across Massachusetts' health-care landscape said the true impact of the deal will not be known for years.