A 28-year-old woman with HIV-1 infection (CD4 count 320 cells/μL, viral load 45,000 copies/mL) has been on a stable regimen of tenofovir/emtricitabine plus efavirenz for 18 months. Repeat CD4 count is now 580 cells/μL with undetectable viral load. She plans to conceive in 6 months and asks about her antiretroviral regimen. Baseline renal function (creatinine 0.8 mg/dL, eGFR 95 mL/min/1.73 m²) and bone density (T-score −1.2 at lumbar spine) are documented. Which change to her antiretroviral regimen is most appropriate?