Implement Salesforce ERROR event for ECA workflows

ERROR event implemented and committed.

What it does:

Catches Salesforce errors and makes the data available in ECA workflows. No more custom event subscribers needed for error handling.

Available tokens:

[error_message], [entity_id], [mapping_info], [operation_type], [failure_details], and others.

Testing:

Created ECA model with both push_fail and error events. Both fire correctly during failures. The error event gives you the detailed context you need for smart error handling.

Files changed:

SalesforceEventsDeriver.php and SalesforceEvent.php

Now you can build error workflows directly in ECA without writing code.