Feat: Add preview as plaintext toggle for Preview As Text (#7102)

## Summary

Adds a toggle to conditionally render the text as Markdown.

## Also...

Fixes some type issues across our myriad Widget types. We should
probably clean those up.

## Example


https://github.com/user-attachments/assets/24fed943-1e79-4ea4-a962-826b06d68761



This could be a good minimal testcase for dynamic widgets @AustinMroz

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7102-WIP-Feat-Add-preview-as-plaintext-toggle-for-Preview-As-Text-2bd6d73d3650810c8b25c84866c8875c)
by [Unito](https://www.unito.io)

tests-ui/tests/renderer/extensions/vueNodes/widgets/composables/useWidgetRenderer.test.ts

@@ -6,6 +6,7 @@ import {
   shouldRenderAsVue,
   FOR_TESTING
 } from '@/renderer/extensions/vueNodes/widgets/registry/widgetRegistry'
+import type { SafeWidgetData } from '@/composables/graph/useGraphNodeManager'
 
 const {
   WidgetAudioUI,
@@ -121,7 +122,10 @@ describe('widgetRegistry', () => {
     })
 
     it('should respect options while checking type', () => {
-      const widget = { type: 'text', options: { someOption: 'value' } }
+      const widget: Partial<SafeWidgetData> = {
+        type: 'text',
+        options: { precision: 5 }
+      }
       expect(shouldRenderAsVue(widget)).toBe(true)
     })
   })