Function fp8_quant_hopper_span 

pub fn fp8_quant_hopper_span(
    groups: u32,
    grid_y: u32,
    block_y: u32,
) -> (u32, u32)

The K-group half-open range one Hopper CTA owns, mirroring the .cu’s gpc/g0/g_end. Exists so fp8_act_quant_tests.rs can assert the launcher’s Y extent and the kernel’s span agree — a partition of 0..L — without a device.