Release hardening: reconcile experiments, verifier cases, and next RC

[aruintelligence]

Track the next repository hardening pass:

• reconcile PR Real-world AML experiments: owned-site remediation + public-site cohort #152 with current main and preserve its real-screen evidence boundaries;
• reconcile PR Make verifier challenge cases language-neutral data #68 without regressing newer verifier-contract hash bindings and migration work;
• move exact verifier mutations into language-neutral data while keeping current integrity checks;
• standardize the real-screen evidence directory contract;
• prepare the next release candidate from one exact commit with checksums and verifier-kit manifest;
• invite external implementations to report PASS / FAIL / MIXED against the reference-code-free challenge;
• keep project-authored evidence, GitHub traffic, and independent adoption claims clearly separated.

Do not treat this issue as a release announcement. Close only after the reconciled work is on main and the exact release checkpoint is documented.