This PR's goal is to improve discoverability of how Zed "remembers" the currently selected agent when hitting `cmd-n` (or `ctrl-n`). Hitting that binding starts a new thread with whatever agent is currently selected. In the example below, I am in a Claude Code thread and if I hit `cmd-n`, a new, fresh CC thread will be started: <img width="500" height="822" alt="Screenshot 2025-11-18 at 1 13@2x" src="https://github.com/user-attachments/assets/d3acd1aa-459d-4078-9b62-bbac3b8c1600" /> Release Notes: - agent: Improved discoverability of the `cmd-n` keybinding to create a new thread with the currently selected agent.