Feature Request: Allow customizing session title format (e.g., project name prefix)

Problem

When working across multiple projects, session titles are auto-generated without any project context. This makes it hard to distinguish which session belongs to which project, especially when many sessions are open.

For example, a session might be titled "Korean greeting conversation" even though it was opened in a specific project directory.

Proposed Solution

Allow users to configure the session title format via CLAUDE.md or settings. For example:

• A rule like [project_name] <auto-generated title> would prefix every session with the project name.
• The project name could be derived from the working directory name or a user-defined value in CLAUDE.md.

Example

Instead of:

• Korean greeting conversation
• Refactor and consolidate...

It would show:

• [app_switcher] Korean greeting conversation
• [my_backend] Refactor and consolidate...

Why This Matters

• Multi-project workflows become much easier to manage
• Session list becomes scannable at a glance
• CLAUDE.md instructions currently cannot control this behavior