Master equation through O(κ 2) by antifield number

Builder/output: master_kappa2.py, P13_master_kappa2.json.

The ${\kappa }^2$ equation is $2(S_0,S_2)+(S_1,S_1)=0$. The engine parts (antifield, ghost and scalar) are exact symbolic, as in p10. Since p11, the gravitational Noether rows are now deterministic: $W_n=s_0{\ell }_{n+2}+s_1{\ell }_{n+1}$ is built as an exact jet polynomial from the sha-checked exports, and $E_{c^{\mu }}(W_n)\equiv 0$ is proved for $n=0,1,2$. The plane-wave evaluation is kept only as a regression control.