forked from 1b-agent/fieldcraft-upstream
A static step's probe gives every node its principal stresses, largest first, beside its stress and von Mises: the eigenvalues of the same nodal stress, from the same function the principal stress contours use. An oracle quantity reads one number at a JSON pointer, so a benchmark whose target is a principal stress (NAFEMS LE6) needs it in a reply. Closes #574. Part of #97.