Feedback: Add ability to submit quick sentiment feedback

I would be nice to have a lightweight feedback category for quick, intentional sentiment signals — distinct from feature requests or bug reports, since positive and negative user feedback, despite not being directly-actionable often, is still a good signal to be able to search through.

Problem

Right now, the feedback system is oriented around actionable items: bugs, feature requests, and discussions. This works well for things worth investigating or debating, but it creates a gap: there's no good way for a user to say "I just noticed this thing and it made me happy" or "this small thing bothers me, but not enough that I want to open a thread about it."

The result is that low-stakes sentiment either goes unshared entirely, or it unnecessarily inflates the feedback backlog with items that don't really need to be acted on.

My Case

I noticed that some models got combined with their "thinking" variants today with further use of the "variants" system. This, to me, cleaned up my favorites a lot and I found the feedback button while trying to say thanks for that, but found no category where my comment made sense.

Why This Matters

Sentiment that doesn't rise to the level of a formal request is still signal. If ten users quietly notice the same small delight — or the same small frustration — that's worth knowing, even if no one felt it warranted opening a thread. This closes that loop without burdening the backlog.