A 28-year-old woman is admitted to a tertiary care hospital in Mumbai 4 hours after ingesting approximately 150 mL of ethylene glycol (antifreeze) in a suspected suicide attempt. She is alert, oriented, and reports mild nausea. Serum osmolality is 320 mOsm/kg (normal 280–300), and arterial pH is 7.32 with HCO₃⁻ 14 mEq/L. Urinalysis shows calcium oxalate crystals. What is the most appropriate immediate management?