Cardano Updates

Deprecates the old-API transaction body surface (the type, its
constructor, and direct producers/consumers) so users are pointed at
'Cardano.Api.Experimental'. Internal modules that still use these
symbols are annotated with -Wno-deprecations to keep -Werror green;
they will be migrated in a follow-up along with the setter family.

Deprecations:
- TxBody (data type), ShelleyTxBody (constructor)
- TxBodyContent (type/constructor)
- createTransactionBody, defaultTxBodyContent
- getTxBody, getTxBodyContent
- BalancedTxBody

The existing pattern-synonym TxBody deprecation message is updated for
consistency with the new messages.

Deprecates the old-API transaction body surface (the type, its
constructor, and direct producers/consumers) so users are pointed at
'Cardano.Api.Experimental'. Internal modules that still use these
symbols are annotated with -Wno-deprecations to keep -Werror green;
they will be migrated in a follow-up along with the setter family.

Deprecations:
- TxBody (data type), ShelleyTxBody (constructor)
- TxBodyContent (type/constructor)
- createTransactionBody, defaultTxBodyContent
- getTxBody, getTxBodyContent
- BalancedTxBody

The existing pattern-synonym TxBody deprecation message is updated for
consistency with the new messages.

- Remove the Test.Gen.Cardano.Api.Internal.Shared module by moving its
  primitives back into Test.Gen.Cardano.Api.Typed where they originally
  lived. Move genTxUpdateProposal and genUpdateProposal back to Typed
  too, restoring the master-style one-way dependency
  Typed -> ProtocolParameters and avoiding the cycle that previously
  required a third module.
- Switch genAlonzoOnwardsPParams to use the constructor-applied form
  (AlonzoOnwardsPParams SNothing <$> ...) instead of <$> pure SNothing.
- Drop now-redundant pragmas in the moved code and the redundant
  Test.Gen.Cardano.Api.ProtocolParameters import in Test.Cardano.Api.CBOR.

Re-export toLedgerUpdate, toLedgerProposedPPUpdates,
fromLedgerProposedPPUpdates and fromLedgerPParamsUpdate from
Cardano.Api.ProtocolParameters to avoid breaking downstream users that
were relying on the previous master surface.

Move toLedgerUpdate and toLedgerProposedPPUpdates definitions back into
Cardano.Api.ProtocolParameters, where they originally lived, and clean
up the argument order of toLedgerUpdate to use plain prefix application.

drop support for x86_64-darwin

The TxBodyProtocolParamsConversionError constructor of TxBodyError
was only used by the toLedgerUpdate call site removed in the previous
commit. With that gone, the constructor is unreachable and can be
removed.

Removes ProtocolParametersUpdate and the conversion functions
toLedgerUpdate, toLedgerProposedPPUpdates, fromLedgerProposedPPUpdates,
toLedgerPParamsUpdate and fromLedgerPParamsUpdate. Use
EraBasedProtocolParametersUpdate instead.

Implement the ToCBOR/FromCBOR instances for EraBasedProtocolParametersUpdate
(previously stubbed with 'error' calls) by routing through the ledger's
PParamsUpdate encoding: toCBOR converts via createEraBasedProtocolParamUpdate,
fromCBOR deserialises a PParamsUpdate and projects back via the existing
fromLedgerPParamsUpdate helper. The instance constraint tightens from
Typeable era to IsShelleyBasedEra era so we can dispatch on the era; this
propagates to UpdateProposal's ToCBOR, FromCBOR and HasTextEnvelope
instances.

Generators and CBOR roundtrip tests are updated to match: cost models
are set to SNothing in genAlonzoOnwardsPParams since they don't survive
CBOR roundtrip (matching the old generator behaviour), and the
prop_roundtrip_UpdateProposal_CBOR test exercises the implemented
instances.

Nixpkgs expects to drop support for intel macs in 26.11.

Nixpkgs expects to drop support for intel macs in 26.11.

The TxBodyProtocolParamsConversionError constructor of TxBodyError
was only used by the toLedgerUpdate call site removed in the previous
commit. With that gone, the constructor is unreachable and can be
removed.