Function from_fused_block 

pub fn from_fused_block(
    fb: &FusedBlock,
    m: usize,
    target: &SpatialTarget,
) -> Result<SpatialProgram, SpatialReject>

A fused transformer block (matmul → requant → bias → relu) as ONE fused compute chain inside the scalar datapath’s fusion window, intermediates streaming through local hand-offs.