pub fn classify_tier(input: &GpuClassInput) -> GpuTierExpand description
Map the gathered GPU signals to a coarse performance tier. Apple silicon is
classified by GPU family generation (family alone cannot separate base from
Pro / Max / Ultra within a generation – a working-set refinement can split
them later); a non-Apple integrated / low-power GPU is the lowest tier; a
discrete GPU is bucketed by dedicated VRAM. An unreporting device (no memory,
not discrete) stays Unknown so the resolver uses the conservative baseline.