Spectral Compression of Charged Black Holes: ρ(Q) for Kerr-Newman

The quasinormal mode analyticity parameter ρ = γ₁/γ₀ ≈ 3 is universal for Kerr (uncharged) black holes [Paper I]. We extend this analysis to Kerr-Newman spacetimes, computing ρ(a, Q) across the full parameter space. The WKB approximation predicts ρ → 3 whenever the standard light ring structure persists. We map the ρ(a, Q) surface and identify [potential deviations / continued universality] near the extremal Kerr-Newman limit where a² + Q² → M².