fix: add entityFactory() convenience method to CloningSpecificationBuilder

Adds a default method that delegates to entityClass() with an empty
config, for cases where only the factory is needed without additional
property definitions. Fixes compilation failure in CI.

Author: theoema

core/src/main/java/ai/timefold/solver/core/api/domain/specification/CloningSpecificationBuilder.java

@@ -38,6 +38,14 @@ <V> CloningSpecificationBuilder<S> solutionProperty(String name, Function<S, V>
     <E> CloningSpecificationBuilder<S> entityClass(Class<E> entityClass, Supplier<E> factory,
             Consumer<CloneableClassBuilder<E>> config);
 
+    /**
+     * Registers an entity class with its no-arg constructor, without additional property definitions.
+     */
+    default <E> CloningSpecificationBuilder<S> entityFactory(Class<E> entityClass, Supplier<E> factory) {
+        return entityClass(entityClass, factory, e -> {
+        });
+    }
+
     /**
      * Registers a {@code @DeepPlanningClone} fact class with its no-arg constructor and property definitions.
      */