Better session names in /resume

Problem

When using /resume to pick up a previous session, the session list is difficult to navigate because sessions lack descriptive names. It's hard to tell which session was about what without opening each one.

Proposed Solution

Automatically generate a short, descriptive name for each session based on the conversation content (e.g., a summary of the main task or topic). This would make it much easier to identify and resume the right session.

Example

Instead of showing generic/timestamp-based entries, the /resume list could show something like:

• "Refactoring auth middleware"
• "Fixing CI pipeline for deploy"
• "Adding dark mode support"

This would greatly improve the UX of session management.