v0.10.0 — the k(3,4) extremal graph is not unique: thirteen rigid witnesses

Answers Question 8.1 of Part G (doi:10.5281/zenodo.21890619) in the negative. At least thirteen pairwise non-isomorphic, rigid extremal graphs on 20 vertices, each independently verified {I_3,TT_4}-free over all triples and transitive quadruples. Includes a short proof that the Paley tournament QR_7 appears in every such graph by force rather than design, and the finding that algebraic blow-up constructions reach only 15 vertices where the truth is 21. Paper: k34add-paper/note.pdf