A 77-year-old woman with dementia residing in a care home develops a productive cough, fever (38.2°C), and increased confusion. Her respiratory rate is 24/min, and crackles are heard at the right lung base. Her CURB-65 score is calculated as 2 (Age ≥ 65, Confusion). According to NICE NG138, what is the most appropriate management setting and initial antibiotic choice?