Added

• Result: ensure/ensureElse to guard Ok values; swap to invert Ok/Err.
• Results: sequence and partition utilities.
• AsyncResult: ensure; AsyncResults.sequence/partition.
• Stream extensions: toResultStream and collectToResult.
• Tiny state management: Loadable (Loading/Data/Error) and LoadableController.

Changed

• Public library now exports stream_extensions.dart and loadable.dart.
• README (EN/ZH) refreshed with new APIs and examples.

Fixed

• Minor doc comments and tests coverage; added tests for all new APIs.

Initial release

• Result with core ops (ok, err, map, flatMap, fold) and utilities (Results.combine, Results.traverse).
• Option with some/none, map/flatMap/fold and utilities.
• Validation with error accumulation and built-in validators.
• AsyncResult (Future of Result) with async chaining; AsyncResults utilities.
• Extensions for String/List/Map/Future/num/bool.