P18: A 5-Dimensional Orbital Structure in Cosmology — Mathematical Closure, Observational Convergence, and the Road to DR3

Corpus-synthesis paper connecting three threads: (i) algebraic closure of the orbital geometry (NT21, Closed); (ii) convergence of three independent observational routes on e≈0.14–0.15 (NT25, Closed); (iii) preliminary separation above the ΛCDM forward-modelled baseline in the eROSITA-DE DR1 cluster power spectrum (NT30, Advanced). The primary prediction ωz=11.1991 awaits DESI DR3 (2027) and Euclid DR1 (October 2026). The model is mathematically closed and physically open.