Cardano Updates

chore: un-ignore test_route_submit_error test

The 228 test_cbor_* functions in external.rs were exact duplicates of
specific.rs: both call verify_one(), which already cross-validates the
Rust (pallas-hardano) decoder against the Haskell (testgen-hs) external
decoder. Keep only test_sanity, which is unique (tests crash/restart logic).

- model/api.rs: From<&ScriptV6> → TryFrom<&ScriptV6> to propagate errors
  instead of panic when neither cbor nor json is provided; also removes
  unused EvaluateTransactionError and TxValidatorV6 (already committed)
- external.rs (tx_evaluator): update V6 script caller to use try_from().transpose()?
- external.rs (error_decoder): move doc comment above #[cfg(test)] attribute

- chain_config.rs: fix by_network_magic (764824073→mainnet, 1→preprod, 2→preview was wrong)
- error_decoder/external.rs: move doc comment above #[cfg(test)] attribute
- model/api.rs: remove dead EvaluateTransactionError and TxValidatorV6; fix logs[0] panic
- evaluate/model.rs: version String → u8 (parse error now handled by serde/axum automatically)
- root.rs, utxos.rs: simplify version handling after type change

- chain_config.rs: expand era=6 comment to explain Cardano era sequence
- cli.rs: add long_help to --evaluator warning against using native (pallas-validate not production-ready)
- Dockerfile: remove trailing whitespace from blank line
- deny.toml: add comment explaining which dep requires LGPL-3.0

- Fix serde error message: 'SerdeError' -> 'JSON error' (less impl-detail leakage)
- Clarify conflicting_ogmios_version error message
- Fix grammar: 'Could not fetching' -> 'Could not fetch' in node/chain_config.rs
- Fix README grammar: 'that are return' -> 'that are returned', 'thes' -> 'this'