> Had I done it manually, there's also no way to prove I created it without LLM help

Of course there is -- ask you about it.

The coolest interview process i ever participated in (at MIT Lincoln Lab) was structured this way, and seems 100% LLM-proof. The interview was: give a talk about a cool/impressive technical thing you did for an hour and then answer questions from the interviewers about it for an hour. No way to succeed there without actually understanding.