Add AI help to the editor

[KingSupernova31]

Add an LLM that runs in the browser and shows warnings in the editor, like "[section] is a typo" or "template 3 generates [card], which seems incorrect".

(Shouldn't check rules correctness LLMs aren't smart enough yet.)

[KingSupernova31]

K, in-browser LLMs are not viable, they're just too slow.