X72-41: Special Cofactor and Piola Vorticity

Picks up Round 40's compression of the Hardy–BMO dual route into the special cofactor commutator 𝒜_C=[u·∇,𝒯_0*]C (STOP-C44), and, rather than treating C as an arbitrary tensor, uses its centered symmetry, incompressibility, and the cofactor's quadratic algebra to look for extra cancellation invisible to the standard CRW/BMO estimates. Proves that the affine first-order increment cancels exactly (the locally smooth commutator is O(ℓ²)), but that the second-order jet curvature of a general rotational branch can be nonzero, so no universal third-order cancellation exists; further proves that the special cofactor's nonlocal scalar projection decomposes exactly into a local pressure-source part plus a Piola-type (div cof=0) vorticity-stress defect. STOP-C45 (Affine-Jet Cancellation/Piola–Vorticity Endpoint Gap) hands the remaining critical endpoint problem to the next round's Piola–vorticity-stress dynamics.