Monaco 0.56 breaks worker imports in Vite build

monaco-editor 0.56 introduced a package exports map:

```JS
"./*.js": "./esm/vs/*.js",
"./*": "./esm/vs/*.js"
```

This remaps `monaco-editor/` → `./esm/vs/.js`. So the existing worker imports in `SandcastleEditor.tsx:21` like `monaco-editor/esm/vs/editor/editor.worker?worker` now resolve to a doubled `esm/vs/esm/vs/editor/editor.worker.js path` that doesn't exist. Rolldown then fails to resolve the path.

Migrating would require rewriting all five worker import paths (to `monaco-editor/editor/editor.worker?worker, etc.`).

Start in SandcastleEditor.tsx at line 21 and inspect all five Monaco worker imports. Run the Vite/Rolldown build to reproduce the resolution failure, then verify that the updated import paths resolve successfully and the build completes without the doubled esm/vs path.

Written by the indexing model from the issue text.