Feature Request: Branch management for conversation resume

Problem

When using the resume feature to go back to a previous turn in a conversation, it creates a new branch. However, once you continue from that point, there's no way to switch back to the original branch.

This means the previous conversation path is effectively "lost" from the UI perspective.

Current Behavior

1. Have a conversation with turns A → B → C → D
2. Resume to turn B
3. Continue with new turns B → E → F
4. Cannot go back to the C → D branch anymore

Proposed Solution

Implement branch management similar to git:

• Allow users to see all conversation branches
• Ability to switch between branches (like git checkout)
• Optionally: ability to name/tag important branches

Use Case

This would be very helpful when:

• Exploring multiple solution approaches for the same problem
• Trying different prompts/directions without losing previous attempts
• Comparing outcomes of different conversation paths