Fix undoOnExecutionFailure default value to true

Corrected default value in createUndoable signature:
- undoOnExecutionFailure defaults to true, not false
- This means auto-undo on failure is enabled by default for undoable commands
- Makes sense for optimistic update pattern

Verified against source: command_it.dart lines 1439, 1504, 1571, 1639

Author: escamoteur

docs/documentation/command_it/command_types.md

@@ -140,7 +140,7 @@ static UndoableCommand<TParam, TResult, TUndoState> createUndoable<TParam, TResu
   ValueListenable<bool>? restriction,
   RunInsteadHandler<TParam>? ifRestrictedRunInstead,
   bool includeLastResultInCommandResults = false,
-  bool undoOnExecutionFailure = false,
+  bool undoOnExecutionFailure = true,
   ErrorFilter? errorFilter,
   ErrorFilterFn? errorFilterFn,
   bool notifyOnlyWhenValueChanges = false,