The shortcut is alt+n: https://github.com/nicobailon/pi-subagents/blame/f974c59da415c8a617773c3ca52a80fc61e05e7f/agent-manager-list.ts#L99

On my Mac's input scheme that's ˜ to compose accented characters. ctrl-n would work.

There's no way to change this -- I'll propose a configuration PR to allow users to override this as an alternative to forking