Release v7.56.3

Added

• The Arc command skill teaches ICommandExceptionMapper for turning an integration's exceptions into a CommandResult, including declining, rollback and correlation behavior. (#710)

Changed

• The Stage sandbox guidance now states exactly what the default engine checks: missing required properties and simple literal validate rules on top-level properties of commands that produce events. It also lists the rules it evaluates with the wrong meaning (numeric min/max, not empty on nested properties) and everything it skips (other rules, concept rules, require, constraints, command and query authorization, the /validate route). Skills previously said it enforced no validation at all. (#709)
• The Arc command and decision-read skills teach that the fresh-identifier guard also covers events written directly through the command's unit of work (IUnitOfWork.AddEvent, AddEventWithNamedTags, AddEvents, eventLog.Transactional.Append and its variants) and nested commands, how a conflicting scope is reported as ConflictingConcurrencyScopes, and that Arc 22.100.0 requires Chronicle 19.65.2 or later. (#710)