Pat Archer knows the routines of residents at the assisted living facility outside Boston where she works, keeping detailed notes to remind them of hairdresser appointments, bridge games and family visits. Having a part-time job isn’t how she envisioned her life at 73. But she enjoys the residents — some of whom are several years her junior. For two decades, Archer worked as an accountant for Sylvania, the lighting manufacturing company. It was a fulfilling career with travel that took her across the country and overseas. She retired in 2020, confident she and her husband could get by on around $2,200 in Social Security benefits and a small monthly pension payment from her job. “I had worked hard for many years and thought I would be fine financially,” she said. Instead, paying bills every month became stressful. Medicare covers only a portion of her diabetes medications. Simple necessities, such as groceries, gas and internet, kept getting more expensive.…