refactor(api): extract Babbage/Conway/Dijkstra parsing into unified helper

Creates parseBabbageOnwardsTxOut helper function to eliminate the final
source of duplication in the FromJSON instance. The three era cases
(Babbage, Conway, Dijkstra) now each call this single helper function.

This completes the refactoring by:
- Reducing the FromJSON instance by ~10 more lines
- Making the code structure clearer with simple era-based dispatch
- Consolidating all Babbage+ era parsing logic in one place
- Maintaining full backwards compatibility with all tests passing

The main case expression now clearly shows the parsing strategy for
each era, with complex logic extracted into well-named helper functions.

Author: newhoggy

cardano-api/src/Cardano/Api/Tx/Internal/Output.hs

@@ -455,22 +455,22 @@ instance IsShelleyBasedEra era => FromJSON (TxOut CtxTx era) where
           <*> return TxOutDatumNone
           <*> return ReferenceScriptNone
       ShelleyBasedEraAlonzo -> alonzoTxOutParser AlonzoEraOnwardsAlonzo o
-      ShelleyBasedEraBabbage -> do
-        alonzoTxOutInBabbage <- alonzoTxOutParser AlonzoEraOnwardsBabbage o
-        mInlineDatum <- parseInlineDatum BabbageEraOnwardsBabbage o
-        mReferenceScript <- o .:? "referenceScript"
-        reconcileDatums BabbageEraOnwardsBabbage alonzoTxOutInBabbage mInlineDatum mReferenceScript
-      ShelleyBasedEraConway -> do
-        alonzoTxOutInConway <- alonzoTxOutParser AlonzoEraOnwardsConway o
-        mInlineDatum <- parseInlineDatum BabbageEraOnwardsConway o
-        mReferenceScript <- o .:? "referenceScript"
-        reconcileDatums BabbageEraOnwardsConway alonzoTxOutInConway mInlineDatum mReferenceScript
-      ShelleyBasedEraDijkstra -> do
-        alonzoTxOutInConway <- alonzoTxOutParser AlonzoEraOnwardsDijkstra o
-        mInlineDatum <- parseInlineDatum BabbageEraOnwardsDijkstra o
-        mReferenceScript <- o .:? "referenceScript"
-        reconcileDatums BabbageEraOnwardsDijkstra alonzoTxOutInConway mInlineDatum mReferenceScript
+      ShelleyBasedEraBabbage -> parseBabbageOnwardsTxOut BabbageEraOnwardsBabbage o
+      ShelleyBasedEraConway -> parseBabbageOnwardsTxOut BabbageEraOnwardsConway o
+      ShelleyBasedEraDijkstra -> parseBabbageOnwardsTxOut BabbageEraOnwardsDijkstra o
    where
+    -- | Parse TxOut for Babbage+ eras
+    -- Handles both Alonzo-style (datumhash/datum) and Babbage-style (inlineDatumhash/inlineDatum) fields
+    parseBabbageOnwardsTxOut
+      :: BabbageEraOnwards era
+      -> Aeson.Object
+      -> Aeson.Parser (TxOut CtxTx era)
+    parseBabbageOnwardsTxOut w o = do
+      alonzoTxOut <- alonzoTxOutParser (convert w) o
+      inlineDatum <- parseInlineDatum w o
+      mReferenceScript <- o .:? "referenceScript"
+      reconcileDatums w alonzoTxOut inlineDatum mReferenceScript
+
     -- | Parse inline datum fields from JSON object
     -- Handles both inlineDatumhash and inlineDatum fields, validating they match
     parseInlineDatum