DCRP81/X72R64: Mesoscale Kelvin Decomposition and the SGS Circulation Bridge

Continuing from the single pure-Navier–Stokes terminal coordinate R_K singled out by DCRP80 (the one-period viscous Kelvin residue K^visc_n), and using the filtered-vorticity commutator architecture from DCRP33 and DCRP20–26, this round performs a mesoscale decomposition of it. It proves the exact three-term decomposition K^visc=M_ℓ+K^fvisc_ℓ+K^sgs_ℓ (endpoint-loop shadowing error, filtered viscous circulation, and subgrid-scale circulation flux), and shows that within the mesoscale window ℓ_n=ε_n^p (0