IV.D135 — Finite-Stage Coherence Functional

At refinement tower stage n, coherence functional V_n: Ω_n → ℝ with gradient-plus-quartic form V_n(ω_n) = ||∂_ω χ_n||² + λ_n(||χ_n||² − v_n²)². Mexican-hat structure emerges from coherence kernel, not postulated.