v0.9.0: operator and principal

Broker SPEC-002 (operator and principal). Breaking: register({ principalName, actsFor? }) replaces owner; actsFor: { ref } registers an agent for one of your users (you become its operator; ref is opaque, no '@'). register() and getClaimStatus() return operatorType, operatorId, principalType, principalId/principalRef; claim status renames ownerTier→principalTier, ownerEmail→principalEmail. completeHandshake() and verifyConsentLocally() return initiatorParties/targetParties; receipts carry participants.*.parties (type Parties). verifyMandate()'s agent: orgDomain→operatorDomain.