Two-Observable Kummer Orbits, Escape from Exceptional Fibers, and Quadratic Joint-Degree Growth

The interpolation slopes of the two BADT layers are algebraically independent observables; the flattening path eventually avoids exceptional higher-dimensional fibers; combined rank-4 Kummer theory gives [Q(α_Q, β_Q) : Q] ≥ c_M·Q² (for Q ≥ Q₀, a non-effective threshold) — the second layer's first rigorous arithmetic gain.