fix: unify schema across batches in JSONStreamDatasource to handle null → concrete type evolution#972

fengrui-z wants to merge 7 commits into

datajuicer:maindatajuicer/data-juicer:mainfrom

fengrui-z:fix/json-stream-schema-lockfengrui-z/data-juicer:fix/json-stream-schema-lockCopy head branch name to clipboard