chore(docs): drop retired export from unused baseline

Author: waleedlatif1

scripts/check-unused-exports.baseline.json

@@ -57,7 +57,6 @@
   "apps/desktop/src/main/window.ts#fitBoundsToWorkArea",
   "apps/desktop/src/main/window.ts#sanitizeBounds",
   "apps/desktop/src/main/windows.ts#registerPopupContents",
-  "apps/docs/components/workflow-preview/index.ts#PreviewBlock",
   "apps/docs/components/workflow-preview/index.ts#PreviewTool",
   "apps/docs/components/workflow-preview/index.ts#PreviewWorkflow",
   "apps/docs/components/workflow-preview/workflow-data.ts#PreviewEdgeData",