Algebraic Phantom Crossing in a Two-Sector Effective Fluid: Cosmological Signatures and the \beta=0 Baseline - Code and Data

v3 (FINAL): Complete numerical and consistency fixes — supersedes v2 CRITICAL BUG FIXES:- Fixed: Planck distance-prior r_* used r_drag amplitude (147.09) instead of r_* (144.4). This inflated Planck χ² from ~6 to ~34 and biased Ω_m to ≈0.29 in all joint fits.- Fixed: r(z_*) integration now uses adaptive scipy.integrate.quad (previously fixed_quad n=64 was insufficient).- Added: CAMB interpolation table for r_*(Ω_m, ω_b, h) — trilinear interpolation with mnu=0. CONSISTENCY CORRECTIONS:- Removed: Mode C (circular DESI-DR2-CPL-prior consistency check; incompatible with manuscript's stated strict B=0 restriction).- Removed: S_8 tension alleviation claim (S_8 = 0.821, Planck-consistent).- Regenerated: All 5 figures with corrected parameters.- Regenerated: CMB TT (peak at ℓ = 220, not 199 — previous search range was truncated). FINAL RESULTS: χ²_min (baseline) = 11.27 (ΛCDM: 17.01) ΔAIC = -1.74 (statistical tie, not decisive) ΔBIC = -0.19 Ω_m = 0.3159 ± 0.0162 (Planck: 0.3153) H_0 = 67.31 ± 1.69 (Planck: 67.36) w_0 = -0.796 (DESI CPL: -0.838) w_a = -0.555 (DESI CPL: -0.62) z_c (68% CL) = 0.400 [0.218, 0.533] z_c (95% CL) = 0.400 [0.047, 0.761] σ_8 = 0.800 S_8 = 0.821 ΔP(k)/P = +1.81% (perturbatively silent) CMB TT first peak = ℓ = 220 (exact match) v2 results (ΔAIC = -16.1, z_c = 0.388, S_8 = 0.727) must be ignored.