Function verify_with_merkle 

pub fn verify_with_merkle(
    src: &Path,
    stored_sig: &MerkleSignature,
) -> Result<bool>

Compare a source file’s Merkle root against a stored signature.

Builds the source Merkle tree using the stored signature’s chunk size, then compares roots. Returns Ok(true) if the roots match (file unchanged), Ok(false) if they differ (file needs resync).