IV.P213 — Lamb Shift Structural Estimate (Proton-Size Contribution)

Proton-size Lamb shift contribution: ΔE = 32α³m_e²/(3m_p²)·m_ec² ≈ 0.0121 meV (~1.1% of total 1057.845 MHz). Uses r_p = 4λ̄_p. Tests proton radius at percent level.