pub fn get_or_env_var_opt(value: Option<String>, key: &str) -> Option<String>Expand description
Returns the provided value if Some, otherwise falls back to reading
the environment variable for the given key.
Unlike get_or_env_var, this function returns None instead of an error
when the environment variable is not set. Use this for optional credentials
where missing values are acceptable (e.g., public-only API clients).