Cardano Updates

Introduce 'Maybe LeiosCert' (mirrored after the existing 'Maybe PerasCert')
as an optional field on the Dijkstra-era 'BlockBody'. Other eras are
unaffected — this is the entire Leios-related ledger change per the
rebase plan's decision #3 (no 'Body'/'BodyInline'/'BodyCertificate' sum,
no early-era touch).

The change spans four pieces, all kept together so the type, codec,
hashing, and lens story land coherent:

- 'LeiosCert' / 'PerasCert' placeholders encode as @encodeListLen 0@
  rather than @encCBOR ()@ — the latter is 'encodeNull' (0xf6), which
  collides with the null-tag of 'encodeNullStrictMaybe' and made
  'SJust LeiosCert' indistinguishable from 'SNothing' on the wire.
  Adds a regression test in 'BaseTypesSpec' covering both certs.
- 'DijkstraBlockBody' carries pre-encoded bytes for body / wits /
  aux-data / is-valid / Leios cert / Peras cert, six slots total
  (numSegComponents = 6). The Leios and Peras cert slots always emit
  a CBOR token (null when absent) so the on-wire layout is fixed.
- Lens setters ('txSeqBlockBodyL', 'leiosCertBlockBodyL',
  'perasCertBlockBodyL') rebuild via the bidirectional
  'DijkstraBlockBody' pattern. The previous setters only updated the
  structural field and silently kept the stale pre-encoded bytes, so
  e.g. setting txs left 'dbbTxsBodyBytes' as the empty list and the
  block on the wire had no transactions even though the in-memory
  rep was correct. Mirrors the Alonzo idiom
  @lens abbTxs (\_ s -> AlonzoBlockBody s)@.
- 'Arbitrary' and 'TreeDiff' instances for the body extended to
  generate / show the new cert slot.

Co-Authored-By: Claude <[email protected]>

Introduce 'Maybe LeiosCert' (mirrored after the existing 'Maybe PerasCert')
as an optional field on the Dijkstra-era 'BlockBody'. Other eras are
unaffected — this is the entire Leios-related ledger change per the
rebase plan's decision #3 (no 'Body'/'BodyInline'/'BodyCertificate' sum,
no early-era touch).

The change spans four pieces, all kept together so the type, codec,
hashing, and lens story land coherent:

- 'LeiosCert' / 'PerasCert' placeholders encode as @encodeListLen 0@
  rather than @encCBOR ()@ — the latter is 'encodeNull' (0xf6), which
  collides with the null-tag of 'encodeNullStrictMaybe' and made
  'SJust LeiosCert' indistinguishable from 'SNothing' on the wire.
  Adds a regression test in 'BaseTypesSpec' covering both certs.
- 'DijkstraBlockBody' carries pre-encoded bytes for body / wits /
  aux-data / is-valid / Leios cert / Peras cert, six slots total
  (numSegComponents = 6). The Leios and Peras cert slots always emit
  a CBOR token (null when absent) so the on-wire layout is fixed.
- Lens setters ('txSeqBlockBodyL', 'leiosCertBlockBodyL',
  'perasCertBlockBodyL') rebuild via the bidirectional
  'DijkstraBlockBody' pattern. The previous setters only updated the
  structural field and silently kept the stale pre-encoded bytes, so
  e.g. setting txs left 'dbbTxsBodyBytes' as the empty list and the
  block on the wire had no transactions even though the in-memory
  rep was correct. Mirrors the Alonzo idiom
  @lens abbTxs (\_ s -> AlonzoBlockBody s)@.
- 'Arbitrary' and 'TreeDiff' instances for the body extended to
  generate / show the new cert slot.

Co-Authored-By: Claude <[email protected]>

The Leios prototype rebase doesn't need 'cardano-ledger-canonical-state',
'cardano-ledger-conformance', 'cardano-ledger-test', 'plutus-preprocessor',
'ledger-state', or 'cardano-ledger-repl-environment'. They depend on
'cardano-cls', whose source-repository-package isn't trivially compatible
with this base — comment them out so the rebase builds cleanly while we
focus on Leios scope.

Co-Authored-By: Claude <[email protected]>

across eras

it across eras

since this is now part of the `StAnnTx` signal