• Config option to change OpenAI completion color in terminal.
• Minor config logic optimization.

You can change color of OpenAI completion by changing DEFAULT_COLOR in ~/.config/shell_gpt/.sgptrc or $DEFAULT_COLOR env, possible options: black, red, green, yellow, blue, magenta, cyan, white, bright_black, bright_red, bright_green, bright_yellow, bright_blue, bright_magenta, bright_cyan, bright_white.

...
DEFAULT_COLOR=magenta