Proposal: add "AI generated" as a flag reason

The author proposes adding a new flag reason to identify content that was substantially generated by large language models (LLMs) rather than authored by humans. They argue that this would address the current issues of either flagging all LLM-touched content as spam or tagging it as vibecoded, which can be problematic. The author believes that flagging AI-generated content as such would help the community better recognize and address this type of low-value content, which they see as a denial of service attack on users' attention.