A 52-year-old woman with a 10-year history of rheumatoid arthritis (RA) on methotrexate and biologics presents with progressive dyspnea over 6 months, dry cough, and fatigue. She denies fever or constitutional symptoms. Physical examination reveals fine crackles at bilateral lung bases. HRCT chest shows bilateral lower lobe predominant usual interstitial pneumonia (UIP) pattern with honeycombing. Serum rheumatoid factor is positive (1:320), anti-CCP antibodies are elevated, and ANA is negative. What is the most likely diagnosis?