CDN-335: The Contraction Test — Adiabatic contraction closes the SLACS mass gap

Last D13 diagnostic: Blumenthal+86 adiabatic contraction of NFW halos (SHMR-assigned M_200, cosmic f_b=0.157) applied to 20 SLACS ETGs. Result: PASS. Median R_DM drops from 0.94 to 0.41 at fiducial c=10, with 19/20 lenses below the 0.60 threshold. Robust across concentrations: c=5 gives 0.58, c=15 gives 0.25, c=20 gives 0.09. The dark-sector halo contracts with baryonic condensation, concentrating mass within R_Ein. At ETG accelerations (g≫a₀), ν(x) is dormant (~9% boost) and the dark sector behaves like standard CDM. D13 CONDITIONALLY PAID. Scale ladder physically explained: dSphs (ν dominant, R≈0), spirals (ν sufficient, R=0), ETGs (ν dormant, contracted halo, R≈0.4), clusters (mixed, R≈0.57). Predecessor: CDN-334 (zenodo.org/records/20778204). Lock: CDN335_CONTRACTION_TEST_LOCKED.