Cardano Updates

Wrap the flaky STAKE_POOLS_SMASH_01 test with hspec's `sequential`
directly in the module so it runs in isolation within the shared
cluster without competing for resources with parallel tests.

- CheckpointsSpec: drop 1 → pattern match with error (not vacuous True)
- SequentialSpec/SharedSpec: BS.drop 1 → BS.uncons with error
- db-bench: restore error on empty range instead of silent "[]"
- RangeSpec: fromJust (also partial) → explicit pattern match
- TxSeq: restore infinite lists instead of truncating to 1001 elements

- Use error with descriptive messages instead of silently changing
  semantics (e.g. returning default values)
- Replace NE.!! with pattern matching in LayerSpec.hs
- Extract minPort/maxPort as top-level definitions to avoid repetition
- Use case pattern matching instead of tail/drop 1 to preserve crash
  semantics on impossible cases

Replace head/tail partial functions with pattern matching or NonEmpty
alternatives in test files to avoid -Wx-partial warnings becoming errors
with -Werror.

Replace head with pattern matching or safe alternatives in:
- db-bench.hs (benchmark labels)
- Integration tests: Byron/Migrations, Shared/Transactions,
  Shared/Wallets, Shelley/Addresses, Shelley/Migrations,
  Shelley/StakePools, Shelley/Transactions, Shelley/TransactionsNew,
  Shelley/Wallets

HLS 2.9.0.0 doesn't support GHC 9.8.4. Update tools index-state
to 2026-01-20 to get HLS 2.13.0.0 which has GHC 9.8.4 support.

GHC 9.8.4 warns about head/tail as partial functions.
Also remove Ord from TxChange since TokenMap doesn't support Ord.

- Add DuplicateRecordFields to Cardano.Write.Tx
- Replace partial functions in CommandLine.hs and BalanceSpec.hs

GHC 9.8.4 warns about head as a partial function.

GHC 9.8.4 requires this extension when exporting types
with duplicate field names.

Replace head with pattern matching or safe alternatives in:
- SlottingSpec.hs
- RangeSpec.hs
- Discovery.hs

HLS 2.13.0.0 supports GHC 9.8.4.