A createCard rule now has a saved command. Its list, swimlane and title
are resolved once by RulesHelper.createCardTarget - which the ordinary
action uses too, so the two cannot drift - and the new card's id is
derived from the rule invocation, so a replay inserts it once. The
creation hook's createCard activity is known before the insert and is
saved with the command, then delivered durably, which runs the new
card's own rules. A target that does not exist is refused, as the
ordinary insert fails at its activity.
Thanks to xet7 !
