Allow renaming session titles in the VS Code extension

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Session titles in the Claude Code VS Code extension are auto-generated from the first message of the conversation, and there's no way to edit them afterward. This makes it hard to find specific sessions later — especially for long-running work that evolved beyond what its first message described, or when several sessions in the same project end up with similar-looking auto-generated titles. I often have to open sessions one by one just to figure out which one I want.

Proposed Solution

Add a "Rename" action to each session in the VS Code extension's session list:

• Right-click a session → "Rename", or a hover action / inline edit on the title
• Typing a new name updates it immediately and persists across reloads
• The custom title should be the same one shown if I open that session via the CLI (claude --resume), so naming stays consistent across surfaces
• Clearing the custom title should fall back to the auto-generated one

Alternative Solutions

• Workaround I use today: I try to make my very first message in a new session double as the title (e.g., "Refactor auth middleware — keep this as the title"), but this is awkward and pollutes the actual conversation.
• Considered: searching the session list by content instead of renaming, but search doesn't help when I'm scanning visually to pick from recent sessions.
• Considered: keeping a separate notes file mapping session IDs to descriptions — too much friction to maintain.

Priority

Low - Nice to have

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

• Platform: VS Code extension on Windows 11
• Related surface: the same renamed title should show up when listing/resuming sessions from the claude CLI, so naming is consistent across the extension and terminal.