[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/error/ErrorOverlay.vue

@@ -64,17 +64,17 @@ import { useI18n } from 'vue-i18n'
 import { storeToRefs } from 'pinia'
 
 import Button from '@/components/ui/button/Button.vue'
-import { useExecutionStore } from '@/stores/executionStore'
+import { useExecutionErrorStore } from '@/stores/executionErrorStore'
 import { useRightSidePanelStore } from '@/stores/workspace/rightSidePanelStore'
 import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
 import { useErrorGroups } from '@/components/rightSidePanel/errors/useErrorGroups'
 
 const { t } = useI18n()
-const executionStore = useExecutionStore()
+const executionErrorStore = useExecutionErrorStore()
 const rightSidePanelStore = useRightSidePanelStore()
 const canvasStore = useCanvasStore()
 
-const { totalErrorCount, isErrorOverlayOpen } = storeToRefs(executionStore)
+const { totalErrorCount, isErrorOverlayOpen } = storeToRefs(executionErrorStore)
 const { groupedErrorMessages } = useErrorGroups(ref(''), t)
 
 const errorCountLabel = computed(() =>
@@ -90,7 +90,7 @@ const isVisible = computed(
 )
 
 function dismiss() {
-  executionStore.dismissErrorOverlay()
+  executionErrorStore.dismissErrorOverlay()
 }
 
 function seeErrors() {
@@ -100,6 +100,6 @@ function seeErrors() {
   }
 
   rightSidePanelStore.openPanel('errors')
-  executionStore.dismissErrorOverlay()
+  executionErrorStore.dismissErrorOverlay()
 }
 </script>