A 72-year-old woman with no prior medical history presents with bright red blood per rectum and hemodynamic stability (BP 130/80 mmHg, HR 88/min). She reports 3–4 episodes of frank bleeding over the past 6 hours, with no abdominal pain or weight loss. Hemoglobin is 11.2 g/dL (baseline unknown). On digital rectal examination, there is bright red blood in the rectum but no masses or hemorrhoids. What is the most appropriate next step in management?