Mandate 0.8.0

Wave 7: agent security. Check decides delegated requests against the agent records, and the
delegation and workload commands that write those records arrive. Each unit was attacked by a
security review.

Added

• Delegation commands. mandate_authz::command decides CreateDelegation,
  RevokeDelegation, RetireAgent, CompleteExecution and ConsumeApproval, and
  mandate_authz::event folds their events into a DelegationProjection that answers
  AgentAuthorityRead, so Check and the token exchange decide against what the commands wrote.
  A delegation's delegator is the verified subject, its scope stays within the delegate's
  applicable ceilings and its lifetime within the smallest max_delegation_ttl. A refusal emits
  nothing; an unknown record refuses exactly like one of another organization. Each command's
  /outcome/denied scenario passes. SupersedeAgentCapabilityCeiling stays deferred until ESS
  can declare a create beside a move in one outcome.
• Workload identity revocation. mandate_model::workload decides RevokeWorkloadIdentity;
  an unknown, foreign or already revoked identity refuses alike, and its /outcome/denied
  scenario passes.
• Durations. mandate_types::Duration::seconds reads an ISO 8601 time duration and refuses
  calendar, signed, fractional, reordered and overflowing forms.

Changed

• Breaking. mandate_authz::CheckRequest gains at, Pdp gains an agent read, and the
  caller-supplied CheckRequest.ceilings is removed: a delegated request, an execution or an
  agent subject is decided through the evaluator's own record checks, with ceilings read by
  agent. A completed, expired, foreign or mismatched execution refuses, and an agent subject is
  bounded by its own ceilings.
• Records of another organization stay undisclosed. A delegation or agent record of another
  organization refuses like an unrecorded one at Check and at the token exchange
  (Denied, no longer TenantMismatch), and Check refuses a disabled subject or actor.
• An execution-bound delegation is refused at Check until an execution can name a delegation
  created after it.
• Conformance: 181 scenarios, 46 passed (40 at 0.7.1), 0 error.