Redshift Tomography of the KBC Void II A Geometric Hypothesis for the Local Expansion Rate

The KBC supervoid (delta_m ~ -0.45, radius ~300 Mpc) raises the local expansion rate by ~1.8% relative to the global background. Including the Local Sheet potential, the total shift is ~6%, moving H0 from 67 to ~72 km/s/Mpc and reducing the Hubble tension from 5sigma to 2sigma. Fitting BAO and supernova data without this local prior biases the dark energy equation of state: the DESI-preferred negative w_a shifts by ~+0.6, reversing its sign. This model predicts a positive w_a and a dipole in the Hubble flow, testable with Euclid.