Give Plutus data its own encoder #614

Summary

Plutus data has no encoder of its own. Data.toCBORBytes turns a Data value into a generic CBOR tree and hands it to the CBOR encoder, which applies one set of options to the whole tree. Some Plutus data rules do not fit that model, so they are missing or live in CBOR.ts:

The node splits this the same way: the ledger delegates Plutus data to the Plutus encoder (cardano-ledger Plutus/Data.hs L86-87, encCBOR (PlutusData d) = fromPlainEncoding $ Cborg.encode d).

Proposal

Give Data its own encoder that walks a Data value straight to bytes:

• Constructor, list, map, integer and byte-string rules as in encodeData, including the four rows above.
• Lists, maps and constructor fields follow the codec options, so PLUTUS_DATA_OPTIONS, CML_DATA_DEFAULT_OPTIONS, CML_DATA_DEFINITE_OPTIONS and CANONICAL_OPTIONS keep their meaning.
• Data.toCBORBytes, Data.toCBORHex, Data.toDatumHash and the Data encode schemas use it. The transaction encoders already join datum and redeemer bytes from Data.toCBORBytes (feat(cbor): write witness datums and redeemer data with TxCodecOptions #610), inline datums do too (DatumOption.ts), so they pick it up without changes.
• Decoding stays as it is: the generic decoder already accepts every form the ledger accepts, and decoded datums keep their original bytes (fix(datum): keep the original bytes of decoded inline datums #603, format replay).
• After the switch, deprecate CBOR.BoundedBytes, so CBOR holds no Plutus data rules.

Order

1. Add the encoder next to the current path and prove it byte-identical to today's output for every data preset on random data, except the cases in the table.
2. Switch Data to it. This fixes Data: constructors with an index above 127 write the tag 102 pair with the wrong header #601 and CBOR: bignum payloads bypass bounded_bytes chunking above 64 bytes #530 and the -2^64 boundary from CBOR: align Data map encoding default and fix negative int bignum boundary #395.
3. Deprecate CBOR.BoundedBytes.
4. Then move the data default to PLUTUS_DATA_OPTIONS (CBOR: align Data map encoding default and fix negative int bignum boundary #395).

Regression test

• Byte identity with the current encoder for every data preset on seeded random Data, outside the table's cases.
• Constr 128 [1] and Constr 1000 [1] under PLUTUS_DATA_OPTIONS equal the cardano-cli 10.5.1 hash-script-data bytes in Data: constructors with an index above 127 write the tag 102 pair with the wrong header #601.
• A 65-byte bignum, -2^64 and 2^64 match cardano-cli and Aiken v1.1.24 serialise_data.
• Devnet: datum hash spends and redeemers built from these values are accepted.