[BUG]: lr init fails if no api key is provided in environment

[GRBurst]

Hey there,

just searched for a linear-cli tool and found this and added it to my project's flake :-)
It is already helpful to me.

If you however run lr init, it crashes when there is no LINEAR_API_KEY defined in the environment. If it is defined, it does not crash, but still prompts you for the key.

To reproduce, just unset the environment key and run init:

unset LINEAR_API_KEY
lr init

Not a big issue, but thought you might want to know ;-)