A 72-year-old woman with a history of diabetes mellitus type 2 (HbA1c 8.2%) and hypertension (on amlodipine and lisinopril) undergoes contrast-enhanced CT chest for evaluation of a nodule. She receives 80 mL of non-ionic low-osmolality contrast medium (iopamidol). Her baseline serum creatinine is 1.8 mg/dL (eGFR 32 mL/min/1.73 m²). On postoperative day 3, her serum creatinine rises to 2.8 mg/dL with minimal urine output. Urinalysis shows muddy brown casts. What is the most likely diagnosis, and which intervention would have been most effective in preventing this complication?