Proposal: add "AI generated" as a flag reason

IMO, the feed is being DoSed by LLM-authored text and vibecoded software. Anecdotally, the community's immune system is currently rejecting these in two ways: adding the vibecoding tag to anything that's been touched at all by an LLM, or flagging posts as spam. I suggest that both these immune responses are problematic in their own way, and that giving us a way to flag specifically LLM generated content would be better. Per the guidance on the lobsters code repo, posting this as a meta first to gauge sentiment. If this is something we'd collectively like, I would be delighted to make the implementation happen. To define what I mean by AI generated: text or code that was substantially not authored by a human mind trying to communicate an idea, but rather by having an LLM expand a prompt into a larger artifact. There is an element of Stewart's "I know it when I see it" in this definition, but https://en.wikipedia.org/wiki/Wikipedia:Signs_of_AI_writing is one laundry list of hallmarks of