Function embedded_decoded_bytes 

pub fn embedded_decoded_bytes(
    emb: &EmbeddedContent,
) -> Result<Vec<u8>, AcdpError>

Decode an EmbeddedContent to its canonical byte form per acdp-data-ref.schema.json content_hash semantics:

• json → JCS-canonicalized bytes
• utf8 → raw UTF-8 bytes of the string
• base64 → base64-decoded bytes of the string