[FEATURE]: Fork/Copy sessions with full context

[MSoares98]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Problem:
When working on a large session with significant accumulated context (file reads, code understanding, conversation history), I sometimes want to explore a tangent or ask a clarifying question without cluttering the main session.

Currently, my options are (afaik):

• Stay in the session: Ask the question, but this adds noise to the conversation and may derail the main task
• Start a new session (/new): Lose all accumulated context and have to rebuild it

Proposed Solution:
Add a /branch or /fork command that:

1. Creates a new session that is an exact copy of the current session (all messages, tool results, file references, etc.)
2. Switches to that new session
3. Leaves the original session untouched
   This would allow:

• Exploring "what if" scenarios without affecting the main workflow
• Asking clarifying questions in isolation
• Testing different approaches from the same starting point

[MSoares98]

This already exists.
Sorry