user preference Color added And added API Key

[Divit-0]

I modified the Aider bot to allow users to customize their preferred colors for input, assistant output, errors, and warnings. Users are now prompted to select colors at startup, enhancing readability and personalization. Additionally, I added a .env file to store a free API key securely, simplifying configuration for new users.

[CLAassistant]

All committers have signed the CLA.