fix: stop suppressing link rendering during node resize (#8780)

## Summary

Stop link flickering when resizing nodes by removing the
`pendingSlotSync` flag assertion from `scheduleSlotLayoutSync`.

## Changes

- **What**: Remove `layoutStore.setPendingSlotSync(true)` from
`scheduleSlotLayoutSync()` in `useSlotElementTracking.ts`. This call was
introduced in #8367 for graph reconfiguration but was also triggered on
every node resize, causing all links to disappear for one frame per
resize tick. The reconfigure path in `app.ts`
(`addAfterConfigureHandler`) still sets the flag explicitly, so
undo/redo link suppression is unaffected.

## Review Focus

The `pendingSlotSync` flag is still managed correctly for graph
reconfiguration: `app.ts:748` sets it before configure, and the
`finally` block flushes it synchronously. The
`flushScheduledSlotLayoutSync` early-return (pendingNodes empty but
graph has nodes) continues to handle late-mounting Vue components during
reconfigure.

## Before

https://github.com/user-attachments/assets/28cfe4d8-f3f0-46f1-a717-5cb81a28dd75



## After




https://github.com/user-attachments/assets/9445fd00-91f8-4d1e-90ac-86d138d29842

Fixes #8696

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8780-fix-stop-suppressing-link-rendering-during-node-resize-3036d73d365081029820ccfd57425a07)
by [Unito](https://www.unito.io)

---------

Co-authored-by: github-actions <github-actions@github.com>

src/renderer/extensions/vueNodes/composables/useSlotElementTracking.ts

@@ -29,9 +29,6 @@ const raf = createRafBatch(() => {
 
 function scheduleSlotLayoutSync(nodeId: string) {
   pendingNodes.add(nodeId)
-  // Re-assert pending flag for late mounts (Vue components mounting after
-  // flushScheduledSlotLayoutSync was called synchronously in onConfigure)
-  layoutStore.setPendingSlotSync(true)
   raf.schedule()
 }