Version tracking migrated to workflow document store

The workflows store previously held version tracking state (versionId and versionData) alongside the document store, creating potential for inconsistency. When saving, publishing, or activating workflows, code had to update both places or risk stale values.

A new useWorkflowDocumentVersionData composable now owns all version tracking. It follows the established apply/public pattern already used for checksum, tags, and other document properties — a reactive state container with event hooks for future extensibility. When version data changes, an event fires so other parts of the system can react.

All consumers across the editor UI have been updated to read and write version data through the document store. A sync-back listener keeps workflow.value.versionId in sync with the document store, maintaining compatibility with the IWorkflowDb interface that expects the versionId on the workflow object itself.

In the editor UI package, components like WorkflowHeaderDraftPublishActions, WorkflowPublishModal, and WorkflowSettings now access version state through the document store. Composable functions like useWorkflowSaving, useWorkflowActivate, and useWorkflowHelpers have been updated accordingly.

This is part of a broader normalization effort — making the document store the single source of truth for workflow document state. The event hook pattern prepares the groundwork for CRDT support in future iterations.