closure yields a resolution witness, not answer evidence

agent-decided, reversible. Protocol.Evidence is renamed Resolution: a witness that a requirement has been legitimately accounted for, supplied by an adequate answer (answer_resolves) or by a valid closure (closure_resolves). The fates answered and closed remain distinct in every account; no theorem says a closed requirement was answered. A single type suffices because nothing downstream distinguishes the two witnesses, while the old name made a closure receipt produce answer evidence. Rejected alternative: separate answer- and closure-evidence types, which nothing consumes.