FIX7 Risk Rollback No-Go Spec

Rollback always owner-gated Level-B, evidence-bound, epoch-incrementing, fail-closed; never deletes history or restores unsafe writer. Layer-specific rollback covers role/owner/ACL, manifest/readiness activation, writer repoint to fail-closed stub, signoff/evidence revoke, capability false, hash/dependency prior-version activation, packet transaction/rollback, epoch no-decrement. Global no-go on missing rollback/evidence, unprovable sets, anchor drift, bypass, unknown dependency/evidence, bad quorum/freshness, missed 15m verifier, pipeline unavailable/manual SQL. Unsafe restore => revoke writer and FIX7_FORWARD_COMPENSATION_BLOCKED.