A 35-year-old woman presents with recurrent pain in the proximal interphalangeal, wrist, elbow, and knee joints with morning stiffness for 3 years. One month ago, she developed fever (39°C), alopecia, and oral ulcers. Examination shows mild swelling of both wrists. Lab results: WBC 2.5×10⁹/L, PLT 74×10⁹/L, urinary protein (++), ESR 80mm/1st hour, elevated CRP, RF 1:64, ANA 1:320. Wrist X-rays are normal. The most likely diagnosis is: