Function decode_dag_cbor 

pub fn decode_dag_cbor(bytes: &[u8]) -> Result<CborValue, CborError>

Decode canonical DAG-CBOR bytes into a CborValue.

This decoder is intentionally strict:

• rejects non-canonical encodings
• rejects floats, tags, and indefinite-length items
• enforces UTF-8 string map keys
• enforces canonical map key ordering

Suitable only for cryptographic / authoritative CBOR.