fix: node preview Vue mode sizing in manager panel (#7611)

## Summary
- Add `lg-node-preview` class to LGraphNodePreview for CSS targeting
- Override absolute positioning in NodesTabPanel to make Vue mode
previews fit within the container
- Apply zoom scaling (0.5) to fit node previews in the manager info
panel

## Test plan
- [ ] Open manager panel and select a node pack with nodes
- [ ] Verify node previews display correctly with Vue mode enabled
- [ ] Verify previews fit within the panel bounds without overflow

## Before


https://github.com/user-attachments/assets/8cd3a201-600d-4f31-9b79-4a480a07d998



## After



https://github.com/user-attachments/assets/b88ee7f2-5e6d-4913-b5a6-fa5fbe3b4dde





┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7611-fix-node-preview-Vue-mode-sizing-in-manager-panel-2cd6d73d36508141843cea046f104746)
by [Unito](https://www.unito.io)

src/components/node/NodePreview.vue

@@ -2,7 +2,11 @@
 https://github.com/Nuked88/ComfyUI-N-Sidebar/blob/7ae7da4a9761009fb6629bc04c683087a3e168db/app/js/functions/sb_fn.js#L149
 -->
 <template>
-  <LGraphNodePreview v-if="shouldRenderVueNodes" :node-def="nodeDef" />
+  <LGraphNodePreview
+    v-if="shouldRenderVueNodes"
+    :node-def="nodeDef"
+    :position="position"
+  />
   <div v-else class="_sb_node_preview bg-component-node-background">
     <div class="_sb_table">
       <div
@@ -92,8 +96,9 @@ import { useWidgetStore } from '@/stores/widgetStore'
 import { useColorPaletteStore } from '@/stores/workspace/colorPaletteStore'
 import { renderMarkdownToHtml } from '@/utils/markdownRendererUtil'
 
-const { nodeDef } = defineProps<{
+const { nodeDef, position = 'absolute' } = defineProps<{
   nodeDef: ComfyNodeDefV2
+  position?: 'absolute' | 'relative'
 }>()
 
 const { shouldRenderVueNodes } = useVueFeatureFlags()