Support server-side evaluation

[ckrause]

Add a checkbox to the editor to enable server-side evaluation. If the user ticks the checkbox, use the eval endpoint from the API spec:
https://api.loda-lang.org/v2/openapi

[neoneye]

That is an interesting idea.

Via the POST /programs/eval endpoint?

The endpoint takes the program as input, so that should be possible.

What about long response times from the server. If it takes 20 seconds to compute 100 terms, then a streaming response is needed.