fix: open image in new tab on cloud fetches as blob to avoid GCS auto-download (#9122)

## Summary

Fix "Open Image" on cloud opening a new tab that auto-downloads the
asset instead of displaying it inline.

## Changes

- **What**: Add `openFileInNewTab()` to `downloadUtil.ts` that fetches
cross-origin URLs as blobs before opening in a new tab, avoiding GCS
`Content-Disposition: attachment` redirects. Opens the blank tab
synchronously to preserve user-gesture activation (avoiding popup
blockers), then navigates to a blob URL once the fetch completes. Blob
URLs are revoked after 60s or immediately if the tab was closed. Update
both call sites (`useImageMenuOptions` and `litegraphService`) to use
the new function.

## Review Focus

- The synchronous `window.open('', '_blank')` before the async fetch is
intentional to preserve user-gesture context and avoid popup blockers.
- Blob URL revocation strategy: 60s timeout for successful opens,
immediate revoke if tab was closed, tab closed on fetch failure.
- Shared `fetchAsBlob()` helper is also used by the existing
`downloadViaBlobFetch`.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9122-fix-open-image-in-new-tab-on-cloud-fetches-as-blob-to-avoid-GCS-auto-download-3106d73d365081a3bfa6eb7d77fde99f)
by [Unito](https://www.unito.io)

src/composables/graph/useImageMenuOptions.ts

@@ -1,6 +1,6 @@
 import { useI18n } from 'vue-i18n'
 
-import { downloadFile } from '@/base/common/downloadUtil'
+import { downloadFile, openFileInNewTab } from '@/base/common/downloadUtil'
 import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import { useCommandStore } from '@/stores/commandStore'
 
@@ -23,7 +23,7 @@ export function useImageMenuOptions() {
     if (!img) return
     const url = new URL(img.src)
     url.searchParams.delete('preview')
-    window.open(url.toString(), '_blank')
+    void openFileInNewTab(url.toString())
   }
 
   const copyImage = async (node: LGraphNode) => {