fix: refresh image previews on media upload nodes when refreshing node definitions (#9141)

## Summary
- When pressing `R` to refresh node definitions, image previews on
LoadImage/LoadVideo nodes now update to reflect external file changes
- Re-triggers the combo widget callback to regenerate preview URLs with
a fresh cache-busting `&rand=` parameter
- Extracts `isMediaUploadComboInput` from `uploadImage.ts` to
`nodeDefSchema.ts` as a shared utility

- Fixes #2082



https://github.com/user-attachments/assets/d18d69ae-6ecd-448d-8d7c-76b2c49fdea5



## Test plan
- [ ] Open a workflow with a LoadImage node and select an image
- [ ] Edit and save the image externally (e.g. in an image editor)
- [ ] Press `R` to refresh node definitions
- [ ] Verify the preview updates to show the edited image

src/extensions/core/uploadImage.ts

@@ -2,27 +2,13 @@ import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import {
   type ComfyNodeDef,
   type InputSpec,
-  isComboInputSpecV1
+  isMediaUploadComboInput
 } from '@/schemas/nodeDefSchema'
 
 import { app } from '../../scripts/app'
 
 // Adds an upload button to the nodes
 
-const isMediaUploadComboInput = (inputSpec: InputSpec) => {
-  const [inputName, inputOptions] = inputSpec
-  if (!inputOptions) return false
-
-  const isUploadInput =
-    inputOptions['image_upload'] === true ||
-    inputOptions['video_upload'] === true ||
-    inputOptions['animated_image_upload'] === true
-
-  return (
-    isUploadInput && (isComboInputSpecV1(inputSpec) || inputName === 'COMBO')
-  )
-}
-
 const createUploadInput = (
   imageInputName: string,
   imageInputOptions: InputSpec