pub const LIVE_SBOX: [[bool; 64]; 10];Expand description
Per-position live S-boxes (computed by the private live_sboxes).
LIVE_SBOX[round][k] for round in 0..10, k in 0..64 (output byte
16·lane + 4·column + row). Exactly 494 entries are true.
crate::sbox_placement walks it to decide where each live box lives.