Environment variables for external editors opened while editing prompt

[pynappo]

I'd like to have the ability to detect whether my editor was opened by crush to edit a prompt, so i can setup specific settings differently (for example, setting up filepath completion on @). I think adding environment variables to the editor process created by crush would be the simplest way to do that. Could just be the AI_AGENT/CRUSH/etc. variables listed in https://github.com/charmbracelet/crush/blob/main/docs/hooks/README.md#input for hooks