Thawing Axion-like Dark Energy from Torsional Electroweak Baryogenesis: Tests at DESI, CMB Birefringence and Structure Growth

v2.0 (May 2026) — major reframing. The original claim of the v1.x series (that the dark-energy scale could be derived from baryogenesis as ρΦ ∼ ρPl η40/3 with C ∼ O(1)) is explicitly retracted in this version: a rigorous Harvey-Turner audit of the relevant electroweak chemical potentials shows that the factorized doublet product κQ9κL3 ≈ -1.24 × 10-8, eight orders of magnitude below the value that would be required. The numerical proximity log(ρΛ/ρPl)/logη ≃ 13.31 ≈ 40/3 is reported as an unexplained coincidence, not as a derivation. What the v2.0 paper does claim. A minimal canonical scalar field Φ with axion-like potential V = Λ4rec[1 - cos(Φ/fΦ)], fΦ ∼ M-barPl, kicked to an initial displacement Φi/fΦ = 1 by the Nieh-Yan torsional residue of electroweak baryogenesis, and coupled to the photon through a Chern-Simons operator (cW/4fΦ)Φ F Ф-tilde, produces: A joint MCMC fit of DESI DR1 BAO + Pantheon+ SH0ES + Planck distance priors yielding w0 = -0.866+0.069-0.067, wa = -0.564+0.295-0.312, Δχ2 = -6.4 vs ΛCDM, non-phantom thawing preferred at 2.1σ. A canonical Klein-Gordon FLRW solution that reproduces (w0, wa) = (-0.904, -0.160). An integrated CMB birefringence β = cW × 6.92°, matching the Eskilt-Komatsu PR4 measurement β = 0.342° ± 0.094° at 0.04σ with cW ≃ 0.0495. A tomographic birefringence prediction βgal(z=1)/βCMB ≃ 0.79, the key signature versus ultralight-axion alternatives. A growth-of-structure suppression Δ(fσ8)/fσ8 ≃ -5.4% at z ≈ 0.5, in the direction of the residual S8 tension. An end of cosmic acceleration at astop = 1.81, tstop - t0 = 11.84 Gyr. A complete catalog of 17 multi-channel signatures (cosmic birefringence tomography, anisotropic β, GW chirality, polarized GW background, exact cT = c, pulsar dipolar radiation bound M* > 1012 GeV, fσ8 tomography, Δα/α structural bound cF < 5 × 10-4cW, null ˙G/G, leptophilic electron EDM de ≃ 3.3 × 10-40 e cm, mass-varying neutrinos, end of acceleration, primordial magnetogenesis, residual lepton/baryon ratio, chiral BH hair). New in v2.0: §9 Harvey-Turner Audit, Appendix A step-by-step derivation, §16 Multi-channel predictions, Appendix B Open Directions (scenarios A-F for a possible future derivation of the cosmological-constant scale within a recoil-style framework). Companion scripts calcolo_C_harvey_turner.py and verifica_predizioni_multicanale.py. Files included: preprint PDF; LaTeX source; supplementary markdown documents (Harvey-Turner derivation, multi-channel predictions catalog, post-MCMC open problems, Nieh-Yan derivation); 19 Python scripts (MCMC, Klein-Gordon, cosmic birefringence, Harvey-Turner, multi-channel verification, distance/BAO/supernovae/CMB-priors test suite); output products excluding raw MCMC chains (omitted for file-size reasons but exactly reproducible from mcmc_full_combined.py). Status. Speculative theoretical preprint by an independent researcher, intended for discussion and independent scrutiny. Not endorsed for arXiv. Disseminated through Zenodo for timestamped archival and DOI citability.