Feature: Auto-generate descriptive session names

Problem

When using /resume to find past sessions, the default identifier is the initial user prompt, which is often not descriptive enough (e.g., "hey", "can you help me with...", or a long rambling message).

Users must manually run /rename to give sessions meaningful names, which is easy to forget and adds friction.

Proposed Solution

Automatically generate a short, descriptive session name based on the conversation context. Options:

1. After first few exchanges: Claude could auto-suggest or auto-set a name based on what's being worked on (e.g., "IS-26522 Vercel DNS Config", "Auth refactor", "Fix payment bug")

1. When working on tracked issues: If the conversation involves a Notion/Linear/GitHub issue, auto-name using the issue ID + short title

1. Semantic summary: Generate a 3-5 word summary of the session topic after the first substantive exchange

Current Behavior

• Default name = first user prompt (often unhelpful)
• Must manually /rename or press R in /resume picker
• Easy to end up with dozens of sessions named "hey" or truncated questions

Desired Behavior

• Sessions automatically get meaningful names based on context
• Users can still override with /rename if needed
• /resume picker becomes actually useful for finding past work

Additional Context

This came up when working on Notion issues - it would be natural for the session to auto-name as "IS-XXXXX [title]" when that context is present.