Cardano Updates

Replace compareOnCBOR's roundtrip through cardano-api
(cardanoTx → Cardano.serialiseToCBOR) with the raw bytes
already stored in SealedTx.serialisedTx. Identical
comparison outcome, one fewer caller of
cardanoTxIdeallyNoLaterThan. Step 1 of SealedTx
decommission plan.

Five-step plan to remove the three remaining Cardano.Api imports from
lib/primitive/lib/Cardano/Wallet/Primitive/Types/Tx/SealedTx.hs by
eliminating the bridge functions (cardanoTxIdeallyNoLaterThan,
cardanoTxInExactEra, sealedTxFromCardano*, getSealedTxBody,
getSealedTxWitnesses, cardanoApiTxToReadTx).

Replace mkUnsignedTx + mkByronWitness/mkShelleyWitness with
mkLedgerTx + mkByronWitnessLedger/mkShelleyWitnessLedger in
the duplicated test module.

All 8 golden hex string tests pass — ledger-native construction
produces byte-identical CBOR to the cardano-api construction.

Replace mkUnsignedTx + mkByronWitness/mkShelleyWitness with
mkLedgerTx + mkByronWitnessLedger/mkShelleyWitnessLedger in
the duplicated test module.

All 8 golden hex string tests pass — ledger-native construction
produces byte-identical CBOR to the cardano-api construction.

Alternative to Transaction.hs that builds transactions using
mkLedgerTx (ledger lenses) instead of Cardano.Api.TxBodyContent.

Implements mkTransactionLedger and constructUnsignedTxLedger with
key-witnessed withdrawals and certificates. Minting, script
witnesses, and reference scripts are TODO.

Remaining cardano-api dependencies (with TODOs):
- signTransaction takes Cardano.NetworkId
- sealWriteTx roundtrips through cardano-api
- certificateFromDelegationAction returns Cardano.Certificate

Replace InAnyCardanoEra Cardano.Tx with EraValue Read.Tx as the
decoded transaction field. The CBOR bytes remain the canonical
representation.

Temporary cardano-api reconstruction functions kept for callers
that haven't migrated yet (cardanoTxIdeallyNoLaterThan,
getSealedTxBody, getSealedTxWitnesses). These deserialize from
bytes on demand.

fromSealedTx in Sealed.hs becomes trivial: just reads the field.