feat: add /scripts/{script_hash}/utxos endpoint
Adds an endpoint listing the UTXOs that hold a given script as a
reference script (CIP-33). These outputs can be used as reference
inputs (CIP-31) to execute the script without including its bytes.
A script may be held by multiple UTXOs, potentially at different
addresses, so the endpoint is paginated.
Response shape mirrors /addresses/{address}/utxos, omitting the
deprecated tx_index field (consistent with tx_content_utxo).
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>