[action] Anthropic restores Mythos 5 access with restrictions after U.S. government negotiations

Anthropic restores access to Mythos 5 following a two-week negotiation with the Trump administration, but only for a limited set of approved organizations. Continues the trend of U.S. regulatory involvement in frontier model availability decisions. Affected: anthropic/mythos-5. Severity: action_required. Verification: verified.