Function moe_grouped_decode_enabled 

pub fn moe_grouped_decode_enabled() -> bool

Kill switch for the grouped-GEMM MoE decode arm. PRESENCE check per the house convention (ATLAS_NO_MOE_GROUPED_DECODE=0 is NOT off), read once per process — this predicate sits in the decode path, and the env::var it replaces ran on every dispatch for MoE models.