V.T179 — ι_τ¹⁵ from Generator Orbit: 15 = dim(τ³) × |generators|

15 = dim(τ³) × |generators| = 3 × 5: canonical interpretation established via generator orbit construction. Each generator contributes ι_τ^{dim(τ³)} = ι_τ³; cycling ℤ/5ℤ through all 5 gives ι_τ¹⁵. SA-i mod-N hierarchy: mod-3 → ι_τ⁹ → θ_QCD=0; mod-5 → ι_τ¹⁵ → η_B. Wave 11 upgrade: generator orbit derivation places 15 = 3×5 on structural footing.