fix: Prevent corruption of workflow data due to checkState during graph loading (#9531)

## Summary

During workflow loading, the workflow data & active workflow object can
be out of sync, meaning any checkState calls will overwrite data into
the wrong workflow.

Recreation steps:
* Open 2-3 workflows
* Enter builder mode > select step
* Select some different inputs on each
* Quickly tap the shift key (this triggers checkState) while switching
tabs
* After a while, you'll see the wrong inputs on the workflows

Alternatively, register an extension that guarantees to call checkState
during the bad phase, run this in browser devtools and switch tabs:
```
window.app.registerExtension({
  name: 'bad',
  async afterConfigureGraph() {
    window.app.extensionManager.workflow.activeWorkflow.changeTracker.checkState()
  }
})
```

## Changes

- **What**: 
- Add loading graph flag
- Prevent checkState calls while loading
- Prevent app mode data sync while loading

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9531-fix-Prevent-corruption-of-workflow-data-due-to-checkState-during-graph-loading-31c6d73d365081e2ab91d9145bf1d025)
by [Unito](https://www.unito.io)

src/stores/appModeStore.ts

@@ -9,6 +9,7 @@ import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
 import { useWorkflowStore } from '@/platform/workflow/management/stores/workflowStore'
 import { useSidebarTabStore } from '@/stores/workspace/sidebarTabStore'
 import { app } from '@/scripts/app'
+import { ChangeTracker } from '@/scripts/changeTracker'
 import { resolveNode } from '@/utils/litegraphUtil'
 
 export const useAppModeStore = defineStore('appMode', () => {
@@ -77,7 +78,7 @@ export const useAppModeStore = defineStore('appMode', () => {
         ? { inputs: selectedInputs, outputs: selectedOutputs }
         : null,
     (data) => {
-      if (!data) return
+      if (!data || ChangeTracker.isLoadingGraph) return
       const graph = app.rootGraph
       if (!graph) return
       const extra = (graph.extra ??= {})