Feat: Show Progress Text on Vue Nodes, Markdown for Preview as Text (#6805)

## Summary

Maps the progressText / text preview to a readonly Markdown widget.

## Review Focus

Anything else to tweak about this while I'm in here?

## Screenshots
<img width="1107" height="593" alt="image"
src="https://github.com/user-attachments/assets/a445c07a-2fcb-480c-976e-bda6ff343f14"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6805-Feat-Show-Progress-Text-on-Vue-Nodes-2b26d73d3650814d93c4f2fbf0e00095)
by [Unito](https://www.unito.io)

src/scripts/domWidget.ts

@@ -303,10 +303,11 @@ export class ComponentWidgetImpl<
     inputSpec: InputSpec
     props?: P
     options: DOMWidgetOptions<V>
+    type?: string
   }) {
     super({
-      ...obj,
-      type: 'custom'
+      type: 'custom',
+      ...obj
     })
     this.component = obj.component
     this.inputSpec = obj.inputSpec