[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/utils/graphTraversalUtil.ts

@@ -4,7 +4,10 @@ import type {
   Subgraph
 } from '@/lib/litegraph/src/litegraph'
 import type { NodeExecutionId, NodeLocatorId } from '@/types/nodeIdentification'
-import { parseNodeLocatorId } from '@/types/nodeIdentification'
+import {
+  createNodeLocatorId,
+  parseNodeLocatorId
+} from '@/types/nodeIdentification'
 
 import { isSubgraphIoNode } from './typeGuardUtil'
 
@@ -359,6 +362,36 @@ export function getNodeByLocatorId(
   return targetSubgraph.getNodeById(localNodeId) || null
 }
 
+/**
+ * Convert execution context node IDs to NodeLocatorIds.
+ * Uses traverseSubgraphPath to resolve the subgraph chain.
+ *
+ * @param rootGraph - The root graph to resolve against
+ * @param nodeId - The node ID from execution context (could be execution ID like "123:456:789")
+ * @returns The NodeLocatorId, or undefined if resolution fails
+ */
+export function executionIdToNodeLocatorId(
+  rootGraph: LGraph,
+  nodeId: string | number
+): NodeLocatorId | undefined {
+  const nodeIdStr = String(nodeId)
+
+  if (!nodeIdStr.includes(':')) {
+    // It's a top-level node ID
+    return nodeIdStr
+  }
+
+  // It's an execution node ID — resolve subgraph path
+  const parts = nodeIdStr.split(':')
+  const localNodeId = parts.at(-1)!
+  const subgraphPath = parts.slice(0, -1)
+
+  const targetGraph = traverseSubgraphPath(rootGraph, subgraphPath)
+  if (!targetGraph) return undefined
+
+  return createNodeLocatorId(targetGraph.id, localNodeId)
+}
+
 /**
  * Finds the root graph from any graph in the hierarchy.
  *