Looks up POPPY_API_KEY in the environment for use with poppy_chat().
Value
The value of POPPY_API_KEY or NA_character_ when the variable is
not set or set to an empty string.
Details
Intended to be passed as the credentials argument to
poppy_chat(), following the ellmer::chat_openai_compatible()
convention of accepting a function that returns a key.
Examples
Sys.setenv(POPPY_API_KEY = "abc123")
get_poppy_api_key()
#> [1] "abc123"