CCEGA Paper 26: The Reflective Surface of Rotating Black Holes is Spherical — Derivation from the Modulus Field Equation in Kerr Geometry

First derivation of an ECO reflective surface position from a physical scalar field equation in Kerr geometry. The modulus field φ(r,θ) is solved numerically in the full Kerr background for spins a* ∈ [0, 0.99]. The radial kinetic term dominates the angular term by a factor 47–412 near the horizon. The surface φ=φ_crit is spherically symmetric to <10⁻¹⁵ angular variation for all spins. Validates Paper 22 ratio table exactly. No angular broadening of GW echoes. First principles derivation — no free parameters.