Reconcile language-neutral verifier cases as Snapshot 3

[aruintelligence]

Purpose

Replay the vetted Snapshot 3 verifier-contract work cleanly on top of current main, after the licensing, real-screen evidence, and release-discipline hardening landed.

What this changes

• publishes conformance/verifier-challenge-cases.json as a language-neutral aml-verifier-challenge-cases/1 corpus;
• preserves the four historical black-box cases and expected outcomes while making exact mutations and evaluation times readable without inspecting canonical JavaScript harness source;
• advances the verifier contract through an explicit Snapshot 2 → Snapshot 3 migration instead of silently rewriting Snapshot 2;
• updates the verifier catalog and lineage while preserving prior snapshots as immutable historical targets;
• updates the black-box conformance harness to consume the published case corpus and report exact challenge, case-corpus, and witness-vector SHA-256 identifiers;
• updates the reference-code-free External Verifier Kit and current-snapshot-aware tests;
• keeps project CI and project-defined PASS results clearly separated from independent external verification.

Rebase safety

This is a clean one-commit replay of the intended #160 file states onto the current main. The intervening main-side hardening did not modify these verifier-contract paths, so no newer main changes are intentionally overwritten.

Evidence boundary

A black-box PASS is compatibility evidence for the exact tested project-defined contract. It is not certification, proof of implementation independence, standards-body approval, scientific validation, regulatory compliance, safety, production suitability, or adoption.

Reference implementations maintained in this repository remain project-controlled evidence. Independent credit requires the separate provenance/independence conditions documented by the project.