Tighter image sizing in vue mode (#8702)

Fixes multiple overlapping issues with both the ImagePreviews (LoadImage
node) and LivePreview (Ksampler node) to eliminate empty space and move
the bahviour to be closer to the litegraph implementation.
- NodeWidgets will no longer no longer flex-grow when it contains no
widgets capable of growing
<img width="278" height="585" alt="image"
src="https://github.com/user-attachments/assets/c4c39805-1474-457b-86d1-b64ecf01319f"
/>

- The number of element layers for LivePreview has been reduced. Sizing
is difficult to properly spread across nested flex levels.
- The ImagePreview and LivePreview now have `contain-size` set with a
min height of 220 pixels (the same as the litegraph implementation).
This allows images to "pillarbox" by increasing width without increasing
height.
  | Before | After |
  | ------ | ----- |
| <img width="360" alt="before"
src="https://github.com/user-attachments/assets/3fe38a20-47d3-4a77-a0db-63167f76b0be"/>
| <img width="360" alt="after"
src="https://github.com/user-attachments/assets/22dc6bf6-1812-49bb-95a1-3febfb3e40dd"
/>|
| <img width="360" alt="before"
src="https://github.com/user-attachments/assets/99b24547-6850-4b46-a972-53411676c78f"
/> | <img width="360" alt="after"
src="https://github.com/user-attachments/assets/0a7783c8-cf93-47aa-8c60-608b9a4b4498"
/>|

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8702-Tighter-image-sizing-in-vue-mode-2ff6d73d3650814196f0d55d81a42e2d)
by [Unito](https://www.unito.io)

---------

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

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

@@ -116,9 +116,10 @@
           <NodeContent :node-data="nodeData" :media="nodeMedia" />
         </div>
         <!-- Live mid-execution preview images -->
-        <div v-if="shouldShowPreviewImg" class="min-h-0 flex-1 px-4">
-          <LivePreview :image-url="latestPreviewUrl || null" />
-        </div>
+        <LivePreview
+          v-if="shouldShowPreviewImg"
+          :image-url="latestPreviewUrl"
+        />
 
         <!-- Show advanced inputs button for subgraph nodes -->
         <div v-if="showAdvancedInputsButton" class="flex justify-center px-3">