Function commit_phase_error_ldr_m 

pub fn commit_phase_error_ldr_m(
    regime: &FriRegime,
    shape: &InstanceShape,
    m: usize,
) -> Option<ErrorBits>

FRI commit-phase per-round error in LDR with explicit proximity parameter m. DKT26 Theorem 5.12 and Appendix B.1–B.2 give the Johnson-regime line-MCA count C = 8·n·(m + 1/2)^3/(3·rho_minus); multiplying by folding − 1 accounts for the polynomial-curve degree of a folding round. We also retain the independent n/|F| bound from [2024/1553] and take the minimum of their security bits. Round-by- round soundness is dominated by round 0 (largest n), so we use n = lde_domain_size for every round. For positive-degree codes at m >= 3, MCA gives fewer security bits and determines this minimum. Reconstruction can instead cap the separate constant-code bound.

Returns None when regime.max_log_arity is 0 (folding factor 1, i.e. no fold at all) — such a regime has no commit-phase round, rather than being indistinguishable from arity 2.