Feature Request: Allow editing/renaming conversation titles

Description

Currently, conversation titles are auto-generated from the first message and cannot be edited afterward. It would be useful to rename past conversation titles for better organization.

Use Case

When revisiting past conversations, auto-generated titles are often not descriptive enough. Being able to rename them would make it much easier to find and organize conversations.

Suggested Solution

• Add a rename option in the conversation history list (VS Code extension sidebar / CLI)
• Or a command like /rename-conversation "new title"