AI-driven luxury frenzy and K-shaped divergence

SF luxury market surging with AI cash, 144 sales over $1M above asking in H1 2026, Atherton at $10M median. South Bay softens (Santa Clara -5.58%, Sunnyvale -8%, San Jose -5% YoY). Marin spillover and Pacifica record sale confirm bifurcation. New: Napa Valley spillover emerging as brokers prep for AI wealth tsunami, with median $925K and institutional interest.