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/renderer/extensions/vueNodes/widgets/components/WidgetMarkdown.vue

@@ -57,7 +57,7 @@ const renderedHtml = computed(() => {
 
 // Methods
 const startEditing = async () => {
-  if (isEditing.value) return
+  if (isEditing.value || widget.options?.read_only) return
 
   isEditing.value = true
   await nextTick()