fix: use WidgetSelectDropdown for models (#6607)

## Summary

As the commit says, the model loaders were broken in cloud if you
enabled Vue Nodes (not a thing I think user does yet).

This fixes it by configuring the `WidgetSelectDropdown` to load so the
user load models like they would load a input or output asset.

## Review Focus

Probably `useAssetWidgetData` to make sure it's idomatic.

This part of
[assetsStore](https://github.com/Comfy-Org/ComfyUI_frontend/pull/6607/files#diff-18a5914c9f12c16d9c9c3a9f6d0e203a9c00598414d3d1c8637da9ca77339d83R158-R234)
as well.

## Screenshots

<img width="1196" height="1005" alt="Screenshot 2025-11-05 at 5 34
22 PM"
src="https://github.com/user-attachments/assets/804cd3c4-3370-4667-b606-bed52fcd6278"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6607-fix-use-WidgetSelectDropdown-for-models-2a36d73d36508143b185d06d736e4af9)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>

tests-ui/tests/composables/useAssetWidgetData.desktop.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it, vi } from 'vitest'
+import { ref } from 'vue'
+
+import { useAssetWidgetData } from '@/renderer/extensions/vueNodes/widgets/composables/useAssetWidgetData'
+
+vi.mock('@/platform/distribution/types', () => ({
+  isCloud: false
+}))
+
+const mockUpdateModelsForNodeType = vi.fn()
+const mockGetCategoryForNodeType = vi.fn()
+
+vi.mock('@/stores/assetsStore', () => ({
+  useAssetsStore: () => ({
+    modelAssetsByNodeType: new Map(),
+    modelLoadingByNodeType: new Map(),
+    modelErrorByNodeType: new Map(),
+    updateModelsForNodeType: mockUpdateModelsForNodeType
+  })
+}))
+
+vi.mock('@/stores/modelToNodeStore', () => ({
+  useModelToNodeStore: () => ({
+    getCategoryForNodeType: mockGetCategoryForNodeType
+  })
+}))
+
+describe('useAssetWidgetData (desktop/isCloud=false)', () => {
+  it('returns empty/default values without calling stores', () => {
+    const nodeType = ref('CheckpointLoaderSimple')
+    const { category, assets, dropdownItems, isLoading, error } =
+      useAssetWidgetData(nodeType)
+
+    expect(category.value).toBeUndefined()
+    expect(assets.value).toEqual([])
+    expect(dropdownItems.value).toEqual([])
+    expect(isLoading.value).toBe(false)
+    expect(error.value).toBeNull()
+    expect(mockUpdateModelsForNodeType).not.toHaveBeenCalled()
+    expect(mockGetCategoryForNodeType).not.toHaveBeenCalled()
+  })
+})