[Feature Request] Add interactive plan refinement stage before full plan generation

Question

**Bug Description**
Plan mode is nice but an initial conversational stage would improve my workflow. When I ask Claude to plan something, it should first present me an initial plan outline, and then ask for my input. I can ask it to explain certain things in more detail, change its approach, add/remove/modify some requirements etc. Once I confirm I have no more input/questions, then it can proceed and present the full final plan for approval. Otherwise, as it is currently, I need to wait for a d