An Explicit-Threshold Candidate Proof Synthesis for the Generic Branch of Lengyel's Fourth Delannoy Valuation Conjecture (reproducibility archive, v5.4)

Candidate proof synthesis of an explicit-threshold strengthening of the generic branch of Lengyel's Conjecture 4 (INTEGERS 21 (2021), #A86) on 2-adic valuations of central Delannoy number differences: v2(D(u*2^(n+1)+b) - D(u*2^n+b)) = n + 2*v2(b(b+1)) for every b>=1, odd positive u, and every n >= max{2, v2(b(b+1))} (Lengyel's conjecture asserts the generic law for n sufficiently large). The archive assembles four separately reproducible modules (ramified Mahler-Taylor bound M3; high-scale signed increment M4; four-chart derivative-residue transport M5a; finite transition certificate M5b with 1,047,440 exhaustively checked residue classes) together with exact reproducers, outputs, SHA-256 manifests, and a complete audit-resolution ledger. v5.2 answered an external GAP (not FAIL) audit; v5.3 and v5.4 add archive-integrity, attribution, and citation repairs from two further independent audits, with no mathematical change. This is a candidate proof, not a referee-validated theorem; see PROOF_STATUS.md.