The Hubble Tension as a Stellar Physics Bias in the Cosmological Braking Theory: Cepheid Period-Luminosity Relation in the Conformal Metric Φ(z) g_μν

In the Cosmological Braking Theory (CBT), matter propagates in the effective metric Φ(z) g_μν with Φ(z) = 1/D(z) ≥ 1 for z < z_c = 6.539. The effective gravitational mass of stellar constituents is m_eff(z) = m₀ √Φ(z), modifying the internal structure of stars formed at redshift z_form > 0. Using standard stellar scaling laws in the conformal metric, we derive two systematic biases on Cepheid variables: (i) an increased pulsation period P_eff = P₀ √Φ(z_form), due to reduced mean density ρ̄_eff = ρ̄₀/Φ; (ii) an increased luminosity L_eff = L₀ Φ(z_form)², due to the mass-luminosity relation L ∝ M⁴. Both biases cause the local distance ladder to overestimate H₀ relative to the CMB value. The combined bias is ΔH₀/H₀ = 2.562 × log₁₀ γ(z_form), where γ(z) = 1/√D(z). For Cepheid host galaxies formed at z_form = 2.24 (consistent with the cosmic star-formation rate peak), this yields ΔH₀ = +6.1 km/s/Mpc — exactly the observed Hubble tension. This constitutes a parameter-free, analytically derived resolution of the Hubble tension within CBT, requiring no new physics beyond the conformal coupling of matter to the EM condensate. The key observational test is a correlation between H₀_apparent and the stellar age of the Cepheid host galaxy, achievable with existing SH0ES data combined with stellar population age estimates.