Near-Koide Structure Across the Standard Model Fermion Spectrum

We extend the Koide structure analysis of our companion paper beyond the charged lepton sector. A systematic scan of all 220 fermion triples from the Standard Model spectrum reveals 11 near-Koide triples with |Q − 2/3| < 1%, led by the charged leptons (6. 2 × 10⁻⁶) and followed by the cross-sector (μ, d, s) at 1. 7 × 10⁻³ and the third-generation quarks (c, b, t) at 2. 8 × 10⁻³. We show that the (c, b, t) near-miss is stable under QCD running from 2 GeV to 10¹³ GeV. We connect the Koide condition b² = 2 to A₄ flavor symmetry VEV alignment. Radiative stability of Q is established at 1-loop QED, with 2-loop corrections δQ/Q ~ 2 × 10⁻⁶ matching the observed deviation. A Monte Carlo analysis (10⁷ trials) yields p = 1. 4 × 10⁻⁵. Companion to: T. Nagy, "Formal Koide Structure: Mass Bounds, Generation Counting, and Neutrino Predictions from the ZN Ansatz" (DOI: 10. 5281/zenodo. 19698012).