nforum quietly stops logging every AI exchange to disk

Until this change, nforum's fork saved the full raw stream of every AI response to a file on disk, no matter where the code was running - live production included. That's two problems at once. The file grows without limit, and, more to the point for legal work, nobody decided what ended up in it: whatever flowed through the model's responses got written down on the server.

nforum's fix switches that logging off unless an engineer deliberately turns it on to debug a problem, which is how this kind of logging is supposed to behave. It's a small change, but it closes a path where sensitive client material could quietly accumulate on disk that nobody was watching.