Implement widget borders in vue (#7322)

Adds support for displaying the "promoted" and "advanced" border
indicators when in vue mode.

Requires some (hopefully minor and generally beneficial) styling changes
to make sure that the widgets are contained within their border.

Note that the 'advanced' functionality sees minimal use and is likely to
be revamped in the future.

<img width="372" height="417" alt="image"
src="https://github.com/user-attachments/assets/8ea1e66b-2a4e-4a16-996f-289a26e39708"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7322-Implement-widget-borders-in-vue-2c56d73d36508187b881f97e373d433b)
by [Unito](https://www.unito.io)

---------

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

src/types/simplifiedWidget.ts

@@ -28,21 +28,23 @@ export interface SimplifiedWidget<
   /** Current value of the widget */
   value: T
 
+  borderStyle?: string
+
+  /** Callback fired when value changes */
+  callback?: (value: T) => void
+
+  /** Optional method to compute widget size requirements */
+  computeSize?: () => { minHeight: number; maxHeight?: number }
+
   /** Localized display label (falls back to name if not provided) */
   label?: string
 
   /** Widget options including filtered PrimeVue props */
   options?: O
 
-  /** Callback fired when value changes */
-  callback?: (value: T) => void
-
-  /** Optional input specification backing this widget */
-  spec?: InputSpecV2
-
   /** Optional serialization method for custom value handling */
   serializeValue?: () => any
 
-  /** Optional method to compute widget size requirements */
-  computeSize?: () => { minHeight: number; maxHeight?: number }
+  /** Optional input specification backing this widget */
+  spec?: InputSpecV2
 }