refactor: consolidate upload helpers

components/UploadZone.tsx

@@ -1,6 +1,7 @@
 'use client'
 
 import type { FolderEntry } from '@/lib/client-types'
+import { revokeEntryUrls } from '@/lib/client-object-urls'
 import { useSecret } from '@/hooks/useSecret'
 import { useFolderEntries } from '@/hooks/useFolderEntries'
 import { useUploadOrchestrator } from '@/hooks/useUploadOrchestrator'
@@ -60,12 +61,7 @@ export default function UploadZone() {
   })
 
   const handleFolderSelected = (entry: FolderEntry) => {
-    entries.forEach((current) => {
-      const urls = new Set<string>()
-      if (current.modelUrl) urls.add(current.modelUrl)
-      Object.values(current.assetUrls || {}).forEach((url) => urls.add(url))
-      urls.forEach((url) => URL.revokeObjectURL(url))
-    })
+    entries.forEach(revokeEntryUrls)
     setGlobalError(null)
     setEntries([entry])
   }