[FEATURE] Collapsible plan preview in plan mode

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The new file tracking feature for plans is awesome! However, when asking follow-up questions or making edits to plans in plan mode, it's hard to see where Claude's response ends and the updated plan begins. I end up scrolling a lot to find the actual answer.

<img width="600" src="https://github.com/user-attachments/assets/e5b07b91-b8d1-43c9-9480-b8eb27163d68" />

Proposed Solution

Add an option to collapse the plan preview section when working in plan mode. This would make it easier to read Claude's responses without the full plan taking up screen space.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)