1.0.0-beta3

Changed

• Every decision on an action request stores its new status (the
  compare-and-set) before any side effect: grants, the new revision,
  notifications. A decision that loses the race against another worker now
  writes nothing even under a host without a transactional unit of work; it
  used to commit the grants first (Laravel integration review, round 2).
• Services logs a warning when no UnitOfWork is given and a store is not
  one of the SDK's in-memory ones, since operations are then not atomic.
• The contract traits' fixture constants are prefixed (CONTRACT_OBJECT,
  CONTRACT_PARTNER, ...) so a host test case with constants of its own can
  use the traits.
• NotificationOutbox and the SPI guide state when enqueue() runs relative
  to the unit of work, that delivery is at least once, and that PSR-14
  listeners run inside the unit of work before the fan-out.