E₆ GUT Cascade Model: 3 Generations = 3 Gauge Breakings

GUT model based on the chain E₈ → E₆ → SO(10) → SU(5) → G_SM where each breaking generates a generation. 13 Q/L parameters + 6 M_R = 19 total (vs 26 in the SM), 16/18 observables at >96%. Falsifiable predictions: δ_CP = 180° (Derived, structural J=0), m_ββ = 2.9 meV, Σm_ν = 0.059 eV, τ(p→e⁺π⁰) ~ 6×10³³ yr (tension with Super-K, factor ~4×), d_e^PMNS = 0 (falsifiable by ACME), r_120 < 1.5×10⁻⁵ (constraint from nEDM). NO-GO: reduction below 13 parameters impossible. Structural tension: V_ub 2.8× off (120_H sector-dependent does not fix). θ₁₃ resolved: was optimizer artifact, baseline gives 100% (ANA_TEO_744/745).