Function encode 

pub fn encode(
    tag: usize,
    base_data: &[u8],
    new_data: &[u8],
    enable_zstd: bool,
) -> Vec<u8> 

Encodes the difference between base data and new data as a compact delta.

Automatically selects the best compression algorithm based on change analysis. Returns a delta that can be applied to the base data to reconstruct the new data.

Arguments

• tag - User-defined metadata value (can be used as history reference, version tag, etc.)
• base_data - The base data to compare against
• new_data - The new data to encode
• enable_zstd - Whether to enable zstd compression for GDelta