Function encode_to_java_bytes 

pub fn encode_to_java_bytes(sketch: &DDSketch) -> Vec<u8> 

Encode a DDSketch into the Java-compatible binary format.

The output follows the encoding order of DDSketchWithExactSummaryStatistics.encode() then DDSketch.encode():

1. Summary statistics: COUNT, MIN, MAX (if count > 0)
2. SUM (if sum != 0)
3. Index mapping (LOG layout): gamma, indexOffset
4. Zero count (if > 0)
5. Positive store bins
6. Negative store bins