[FEATURE] support plan mode

[difro]

Feature Description

When in plan mode, claude asks to review the plan in Nvim like following.

ctrl-g to edit in Nvim · ~/.claude/plans/optimized-marinating-scott.md

I'd like this to open up in my connected nvim session.
Currently ctrl-g just fires up a new nvim session inside cc terminal.

Use Case

ability to edit plan in connected nvim session

Proposed Solution

If you have ideas about how to implement the feature, share them here.

Alternatives Considered

Have you considered any alternative solutions or workarounds?

Additional Context

Add any other context, screenshots, or examples about the feature request here.