[refactor] Extract executionErrorStore from executionStore (#9060)

## Summary
Extracts error-related state and logic from `executionStore` into a
dedicated `executionErrorStore` for better separation of concerns.

## Changes
- **New store**: `executionErrorStore` with all error state
(`lastNodeErrors`, `lastExecutionError`, `lastPromptError`), computed
properties (`hasAnyError`, `totalErrorCount`,
`activeGraphErrorNodeIds`), and UI state (`isErrorOverlayOpen`,
`showErrorOverlay`, `dismissErrorOverlay`)
- **Moved util**: `executionIdToNodeLocatorId` extracted to
`graphTraversalUtil`, reusing `traverseSubgraphPath` and accepting
`rootGraph` as parameter
- **Updated consumers**: 12 files updated to import from
`executionErrorStore`
- **Backward compat**: Deprecated getters retained in `ComfyApp` for
extension compatibility

## Review Focus
- Deprecated getters in `app.ts` — can be removed in a future
breaking-change PR once extension authors migrate

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9060-refactor-Extract-executionErrorStore-from-executionStore-30e6d73d36508101973de835ab6b199f)
by [Unito](https://www.unito.io)

src/components/TopMenuSection.vue

@@ -169,6 +169,7 @@ import { useSettingStore } from '@/platform/settings/settingStore'
 import { app } from '@/scripts/app'
 import { useCommandStore } from '@/stores/commandStore'
 import { useExecutionStore } from '@/stores/executionStore'
+import { useExecutionErrorStore } from '@/stores/executionErrorStore'
 import { useQueueStore, useQueueUIStore } from '@/stores/queueStore'
 import { useRightSidePanelStore } from '@/stores/workspace/rightSidePanelStore'
 import { useSidebarTabStore } from '@/stores/workspace/sidebarTabStore'
@@ -189,6 +190,7 @@ const { toastErrorHandler } = useErrorHandling()
 const commandStore = useCommandStore()
 const queueStore = useQueueStore()
 const executionStore = useExecutionStore()
+const executionErrorStore = useExecutionErrorStore()
 const queueUIStore = useQueueUIStore()
 const sidebarTabStore = useSidebarTabStore()
 const { activeJobsCount } = storeToRefs(queueStore)
@@ -262,7 +264,7 @@ const shouldShowRedDot = computed((): boolean => {
   return shouldShowConflictRedDot.value
 })
 
-const { hasAnyError } = storeToRefs(executionStore)
+const { hasAnyError } = storeToRefs(executionErrorStore)
 
 // Right side panel toggle
 const { isOpen: isRightSidePanelOpen } = storeToRefs(rightSidePanelStore)