feat: add hideOutputImages flag for nodes with custom preview (#8857)

## Summary

Prerequisite for upcoming native color correction nodes (ColorCorrect,
ColorBalance, ColorCurves) which render their own WebGL preview and need
to suppress the default output image display while keeping data in the
store for downstream nodes.

## Screenshots (if applicable)
before
<img width="980" height="1580" alt="image"
src="https://github.com/user-attachments/assets/2e08869f-1cad-4637-8174-96d034da524c"
/>

after
<img width="783" height="1276" alt="image"
src="https://github.com/user-attachments/assets/3f9b50ee-268c-48f4-9e63-89ef8d732157"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8857-feat-add-hideOutputImages-flag-for-nodes-with-custom-preview-3076d73d365081a2aa55d34280601b47)
by [Unito](https://www.unito.io)

Co-authored-by: Alexander Brown <drjkl@comfy.org>

src/renderer/extensions/vueNodes/components/LGraphNode.vue

@@ -656,7 +656,8 @@ const nodeMedia = computed(() => {
   const newOutputs = nodeOutputs.nodeOutputs[nodeOutputLocatorId.value]
   const node = lgraphNode.value
 
-  if (!node || !newOutputs?.images?.length) return undefined
+  if (!node || !newOutputs?.images?.length || node.hideOutputImages)
+    return undefined
 
   const urls = nodeOutputs.getNodeImageUrls(node)
   if (!urls?.length) return undefined

src/types/litegraph-augmentation.d.ts

@@ -177,6 +177,8 @@ declare module '@/lib/litegraph/src/litegraph' {
     isLoading?: boolean
     /** The content type of the node's preview media */
     previewMediaType?: 'image' | 'video' | 'audio' | 'model'
+    /** If true, output images are stored but not rendered below the node */
+    hideOutputImages?: boolean
 
     preview: string[]
     /** Index of the currently selected image on a multi-image node such as Preview Image */