Remove legacy TxOut from Compatible and Experimental APIs

[Jimbo4350]

Changelog

- description: |
    Remove legacy `TxOut ctx era` from the Compatible and Experimental APIs.

    `createCompatibleTx` now takes `[Exp.TxOut (ShelleyLedgerEra era)]`
    plus an explicit `Map L.DataHash (L.Data ...)` for supplemental
    datums, mirroring how it already takes `Exp.TxCertificates` /
    `Exp.TxVotingProcedures` / `Exp.TxProposalProcedures`.

    Deletes legacy bridge helpers from `Cardano.Api.Experimental.Tx`:
    `fromLegacyTxOut`, `legacyDatumToDatum`, `supplementalDatumFromLegacy`,
    `toLedgerDatum`, `DatumDecodingError`. They were re-exported only
    via the experimental namespace, whose stability contract permits
    breaking changes.

    The legacy `TxOut ctx era` type itself is **unchanged** — `UTxO`,
    `Tx` body construction, fee/balancing, `LedgerState`, and Byron all
    still depend on it.
  type:
   - breaking
  projects:
   - cardano-api

Context

data TxOut ctx era (from Cardano.Api.Tx.Internal.Output) is still load-bearing across Cardano.Api.UTxO, Cardano.Api.Tx.Internal.Body, fee/balancing helpers, LedgerState, and Byron — roughly 230 references in cardano-api/src after filtering — so deprecating it wholesale is not currently practical. The entire UTxO era = Map TxIn (TxOut CtxUTxO era) abstraction depends on it.

The Experimental API has already introduced its own GADT wrapper at Cardano.Api.Experimental.Tx.Internal.BodyContent.New:

data TxOut era where
  TxOut :: L.EraTxOut era => L.TxOut era -> TxOut era

— a thin wrapper over the ledger's L.TxOut. The Experimental code was internally consistent and only referenced legacy TxOut in a handful of migration bridge helpers. The Compatible API (Cardano.Api.Compatible.Tx) still threaded [TxOut CtxTx era] through createCompatibleTx, createCommonTxBody, and convScriptData'.

This PR removes legacy TxOut from both Compatible and Experimental:

1. createCompatibleTx now takes [Exp.TxOut (ShelleyLedgerEra era)] + Map L.DataHash (L.Data (ShelleyLedgerEra era)) for supplemental datums. The legacy TxOut CtxTx era bundled supplemental datums inside outputs, which convScriptData' extracted via [d | TxOut _ _ (TxOutSupplementalDatum _ d) _ <- txOuts'] and folded into TxBodyScriptData. Exp.TxOut intentionally does not carry supplemental datums (only the datum hash; the full datum lives in the witness set), so callers now thread them in explicitly — matching how ledger TxDats actually work.

2. Deletes the legacy bridge helpers from Cardano.Api.Experimental.Tx:

   • fromLegacyTxOut
   • legacyDatumToDatum
   • supplementalDatumFromLegacy
   • toLedgerDatum
   • DatumDecodingError

   These existed solely to convert legacy TxOut CtxTx era / TxOutDatum CtxTx era values into the new world. With the Compatible API no longer accepting the legacy type, no in-repo caller remains. They were re-exported only via Cardano.Api.Experimental.Tx — they are not part of top-level Cardano.Api, and the experimental namespace explicitly permits breaking changes.

After this PR, neither Cardano.Api.Compatible.* nor Cardano.Api.Experimental.* references OldApi.TxOut / TxOut CtxTx era.

How to trust this PR

# Clean build under -Werror across all packages
cabal build all -j4

# Targeted property test for createCompatibleTx
cabal test cardano-api-test --test-options="-p createCompatibleTx"

# Audit: zero legacy TxOut references in Compatible/Experimental sources
rg 'OldApi\.TxOut|TxOut CtxTx|TxOut ctx era' \
   cardano-api/src/Cardano/Api/Compatible \
   cardano-api/src/Cardano/Api/Experimental
# (The only hit should be a haddock comment in Compatible/Tx.hs
#  documenting the migration — intentional.)

Checklist

• Commits are well-sequenced and each commit message is informative
• New code is covered by existing tests (the prop_createCompatibleTx_preserves_all_certs Hedgehog property still passes 100 cases)
• Self-reviewed the diff
• Code formatted with fourmolu
• Builds clean under -Werror

[Copilot]

Pull request overview

Removes the legacy TxOut ctx era surface from the Compatible and Experimental exposed APIs, shifting createCompatibleTx to consume the experimental ledger-TxOut wrapper plus an explicit supplemental-datums map, and deleting now-obsolete legacy conversion helpers from the experimental namespace.

Changes:

• Updated Cardano.Api.Compatible.Tx.createCompatibleTx to accept [Exp.TxOut (ShelleyLedgerEra era)] and an explicit Map L.DataHash (L.Data (ShelleyLedgerEra era)) for supplemental datums (instead of extracting them from legacy outputs).
• Removed legacy TxOut/datum bridge helpers from Cardano.Api.Experimental.Tx and Cardano.Api.Experimental.Tx.Internal.BodyContent.New.
• Adjusted the property test to pass mempty for the new supplemental-datums parameter, and added a Herald changelog fragment classifying this as breaking.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
cardano-api/test/cardano-api-test/Test/Cardano/Api/Experimental/Fee.hs	Updates createCompatibleTx test call site for the new supplemental-datums argument.
cardano-api/src/Cardano/Api/Experimental/Tx/Internal/BodyContent/New.hs	Removes legacy TxOut/datum conversion helpers and related exports/imports.
cardano-api/src/Cardano/Api/Experimental/Tx.hs	Stops re-exporting the removed legacy conversion helpers from the exposed Experimental API.
cardano-api/src/Cardano/Api/Compatible/Tx.hs	Changes createCompatibleTx/createCommonTxBody to use experimental TxOut and threads supplemental datums explicitly into script data.
.changes/20260514_cardano_api_remove_legacy_txout_from_compat_and_experimental.yml	Adds a breaking-change changelog fragment describing the API removals/signature change.

[palas]

It all looks good, and I can see you already have IntersectMBO/cardano-cli#1376 ready to adapt to the changes and it also compiles