[Feature Request] Add ability to save execution plan without running implementation

Question

**Bug Description**
Claude Code should offer an easy way to SAVE the plan made in plan mode.

I usually start with planning a specification/change but I don't want to immediately execute it.

Even if I explicitly tell Claude that "this is a planning session, the goal is to write a specificaton" it just goes on and tries to implement everything.

What about adding a menu item to "Claude has written up a plan": "Just save the plan into whatever.md`

Or adding a command like `/save-plan`.

Or whate