Gate 4 / Deliverable 4: contact moments

Odd moments vanish by evenness. ${\Pi }_w+L={\Pi }_{\mathrm{tr}}$; $\partial ({\Pi }_w+L)=0$ both pairs (kernel_two_point_Ward; not functional ST4b). $L$ order $\le 4$; kernel-divergence contact bound on $\partial L$ is five. Formal transpose (not $L^2$ adjoint). $L$ not claimed Lorentz covariant. $C_L=\frac{1}{2}\int hLh$ (gh$=0$, even); $s_0{C}_L$ not evaluated. Kernel CT $\ne$ bulk BV restore.