Document the ExternalReport format based on analysis of 6 sample exports
(empty, withEmptySKD, withSimpleSKD, withModuleAndForm, withAttr, ERP report).
Covers differences from EPF: ClassId, Properties, GeneratedType naming,
report-specific form properties (ReportFormType, ReportResult, DetailsData),
object attributes, and module events.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>