fix: export enums required to implement a TerminalMouserHandler

lib/core.dart

@@ -11,6 +11,8 @@ export 'src/core/escape/handler.dart';
 export 'src/core/escape/parser.dart';
 export 'src/core/input/handler.dart';
 export 'src/core/input/keys.dart';
+export 'src/core/mouse/button.dart';
+export 'src/core/mouse/button_state.dart';
 export 'src/core/mouse/handler.dart';
 export 'src/core/mouse/mode.dart';
 export 'src/core/state.dart';