brainchop-cli sweep over model channel counts

[spikedoanz]

https://trendscenter.slack.com/archives/C09RX1YNS77/p1762806399740889

we need to figure out why 21 chan 104 labels model doesn't work, or why 30 chan + model doesn't work.
the obvious solution is to sweep over channel counts until we get a model that actually works (matches metal spec)