Session sidebar: auto-title sessions based on conversation context and group by repo

Feature Request

What I'd like

1. Auto-title sessions from conversation context — Instead of defaulting to "Untitled session", the sidebar title should be generated from the actual conversation topic (similar to how ChatGPT and other AI interfaces name conversations based on the first exchange).

1. Group sessions by repository — When working inside a git repo, sessions should be organized/divided in the sidebar by the repo they were started in, so it's easy to find past conversations scoped to a specific project.

Why

Right now every session shows as "Untitled session" in the left sidebar, making it impossible to find previous conversations without opening each one. If I'm working across multiple repos, there's no way to filter or group sessions by project.

Expected behavior

• Session title reflects the conversation content (e.g. "PR coverage analysis", "StickyFooter bug fix")
• Sessions are grouped or filterable by the active git repository at the time the session was started