Function parseUrToCbor

Parse any UR into CBOR for use as structured data (e.g., provenance mark info).

This function converts any UR type into a CBOR value:

• For known UR types (envelope, digest, etc.), looks up the CBOR tag from the tag store
• For unknown UR types, requires cborTagValue parameter
• Returns the UR's CBOR content wrapped in the appropriate CBOR tag