fix: Prune invalid builder mappings on load (#9376)

## Summary

- extract resolveNode to reusable util
- remove mid builder pruning
- handle missing widgets with label

## Review Focus

`resolveNode` was simplified for subgraphs by calling getNodeById on
each of the subgraphs instead of searching their inner nodes manually.

## Screenshots (if applicable)

"Widget not visible"
<img width="657" height="822" alt="image"
src="https://github.com/user-attachments/assets/ab7d1e87-3210-4e54-876a-07881974b5c7"
/>
<img width="674" height="375" alt="image"
src="https://github.com/user-attachments/assets/c50ec871-d423-43d6-8e1e-7b1a362f621c"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9376-fix-Prune-invalid-builder-mappings-on-load-3196d73d3650811280c2d459ed0271af)
by [Unito](https://www.unito.io)

src/renderer/extensions/linearMode/LinearControls.vue

@@ -26,6 +26,7 @@ import { useQueueSettingsStore } from '@/stores/queueStore'
 import { cn } from '@/utils/tailwindUtil'
 import { useAppMode } from '@/composables/useAppMode'
 import { useAppModeStore } from '@/stores/appModeStore'
+import { resolveNode } from '@/utils/litegraphUtil'
 const { t } = useI18n()
 const commandStore = useCommandStore()
 const executionErrorStore = useExecutionErrorStore()
@@ -68,11 +69,7 @@ const mappedSelections = computed(() => {
       ([id]) => id === nodeId
     ).map(([, widgetName]) => widgetName)
     unprocessedInputs = unprocessedInputs.slice(inputGroup.length)
-    const node =
-      app.rootGraph.getNodeById(nodeId) ??
-      [...app.rootGraph.subgraphs.values()]
-        .flatMap((sg) => sg.nodes)
-        .find((n) => n.id == nodeId)
+    const node = resolveNode(nodeId)
     if (!node) continue
 
     const nodeData = nodeToNodeData(node)