pub fn encode_into(out: &mut Vec<u8>, src: &[u8], kf: u32)Expand description
Encodes binary bytes into printable 0x20..=0x7E chars, appending to out.
Branchless scalar tail: the leader char is always stored, the follower
slot always written (garbage when unused, overwritten by the next
leader), and the write cursor advances by 1 + escape — no mispredicted
branches on the ~50/50 escape mix.