Add base pill for entire response object in Assign

[matKlju]

AS A Service creator

I WANT the Assign element to provide a pill representing the entire response object

SO THAT I can reference or pass the full response as a single variable when needed, in addition to using split field-level pills

Description

Currently, Assign automatically parses API responses into multiple granular pills for easier access. However, there is no way to reference the entire response object as a single pill. A base/root response pill should always be available alongside the parsed pills.

Acceptance Criteria

• Assign generates a base response pill representing the full response object
• Base pill coexists with existing parsed (field-level) pills
• Base pill can be dragged and referenced like any other pill
• Works for:
  • Object-root responses
  • Array-root responses
• Base pill value equals the unmodified response payload