feat: code splitting optimization - reduce initial bundle by 36% (#8542)

## Summary

Reduces initial module preload from 12.94 MB to 8.24 MB (-4.7 MB, -36%).

## Changes

- Split vendor chunks for better cache isolation (firebase, sentry,
i18n, zod, etc.)
- Exclude heavy optional chunks from initial preload: THREE.js, xterm,
tiptap, chart.js, yjs
- Lazy load 16 dialog components in dialogService
- Add \endor-yjs\ chunk for CRDT library

## Metrics

| Metric | Before | After |
|--------|--------|-------|
| Initial preload | 12.94 MB | 8.24 MB |
| vendor-other | 4,006 KB | 2,156 KB |
| dialogService | 1,860 KB | 1,304 KB |

All excluded chunks still load on-demand when their features are used.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8542-feat-code-splitting-optimization-reduce-initial-bundle-by-36-2fb6d73d36508146aaf7fdaed3274033)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: github-actions <github-actions@github.com>

src/components/load3d/Load3dViewerContent.vue

@@ -121,8 +121,9 @@ const mutationObserver = ref<MutationObserver | null>(null)
 
 const isStandaloneMode = !props.node && props.modelUrl
 
+// Use sync version since useLoad3dViewer is already imported (module is loaded)
 const viewer = props.node
-  ? useLoad3dService().getOrCreateViewer(toRaw(props.node))
+  ? useLoad3dService().getOrCreateViewerSync(toRaw(props.node), useLoad3dViewer)
   : useLoad3dViewer()
 
 const { isDragging, dragMessage, handleDragOver, handleDragLeave, handleDrop } =