Function jaccard_batch4 

pub fn jaccard_batch4(
    a: &BoundingBox,
    boxes: &[BoundingBox; 4],
    iou: f32,
) -> [bool; 4]

Batch IoU check: test one reference box a against 4 candidate boxes.

Returns a 4-element array of booleans: result[i] is true if jaccard(a, boxes[i], iou) would return true.

On aarch64, uses NEON vmaxq_f32/vminq_f32 for vectorized intersection computation. On other architectures falls back to 4 scalar jaccard calls.