Paper CCLXXV: Carbon-to-Oxygen from the kappa=0->kappa=-1 Boundary -- Extending the Nico Isobaric Sector to the alpha-Chain, a Hard C/O Ceiling of Unity, and the z=6.625 Test (LAP1-B)

The Nico sector (Paper CLIX) derives Fe-group anomalies (10-20% [Ni/Fe] CCSN overproduction, presolar grain delta(61Ni/58Ni), Mn/Ni tension) from isobaric Co->Ni transmutation at the kappa=0->kappa=-1 G2-permutohedron boundary via the H- square-face sector with the zero-parameter cross-term sqrt6/28. That sector is Fe-group only. We extend it to the light alpha-chain. The alpha particle (4He, four nucleons) is a quaternion unit (dim H=4); 12C=3 alpha closes on the three imaginary quaternion axes i,j,k (the same transverse triad carrying sigma_T2*=(1/2)^3 in CCXLVII/CCLXVIII), while 16O=4 alpha requires also closing the longitudinal real axis. The carbon-burning step 12C(a,g)16O is one additional valve-gated kappa-crossing carrying the canonical Fano coefficient sigma_e7=1/2, so the steady-state ratio is C/O=(1-p)/p=1 (p=1/2): a hard ceiling, log(C/O)->0, in the pristine metal-free limit, declining toward solar (C/O=0.55, N_eff=1.50 crossings) as enrichment adds crossings. Test: LAP1-B at z=6.625 (Nakajima et al. 2026, Nature 653), the most chemically primitive star-forming galaxy known (12+log O/H=6.31, 4.2e-3 solar), has log(C/O)=-0.07(+0.16/-0.24), sitting on the predicted ceiling at 0.44 sigma, on the CEMP/UFD locus above the ordinary trend. Predictions: P1 hard ceiling C/O<=1 for the alpha-channel (CEMP with C/O>>1 needs a separate channel); P2 the C/O(N) relation approaches the ceiling asymptotically at lowest O/H; P3 LAP1-B log(C/O)=0.00, falsified if tightened below ~-0.25; P4 cross-sector -- C/O elevation correlates positively with the CLIX [Ni/Fe] excess in the same population (same boundary, same event), a link absent from standard yields. Honest scope: load-bearing assumption is that 12C(a,g)16O is one valve-gated crossing at exactly 1/2 (sensitivity: +-0.05 in p moves log C/O by ~0.09 dex); the channel cannot reach C/O>>1; LAP1-B's hard ionizing field (stellar-SED) is outside this abundance law; single data point at large uncertainty (CIV/[OIII]=4.2+-1.8). Zero free parameters (sigma_e7=1/2 reused). Framework count: 276 numbered papers. Part of the One-Octonion Brane-Bulk Framework series. Anchor DOI: 10.5281/zenodo.19120873. Community: one-octonion-brane-bulk. Author: Bharathi Dasan Jagadeesan, M.D., University of Minnesota. ORCID: 0000-0002-1143-941X.