Securely route Anthropic API key to public instance

The web terminal interface to the data generator allows setting a temporary Anthropic API key, so it works on a public instance. The web GUI, on the other hand, does not, so it is not yet possible to use data generator functions through the web GUI on a public instance.

While implementing a solution, care should be taken to ensure the key is never transmitted in plaintext or otherwise exposed to other users or third parties.