Function act_quant_inplace 

pub fn act_quant_inplace(x: &mut [f32])

2026-09-25: The shims’ act_quant with a power-of-two scale, in place: per block of FP8_BLOCK, scale = the power-of-two ceiling of amax / 448 (amax floored at 1e-4), values to e4m3 (RNE, clamped), then dequantised and rounded to bf16.