Support immutable entities, readonly stubs, persist return type

- Change persist() return type from bool to object (matches Data)
- Add readonly entity test stubs (ReadOnlyAuthor, ReadOnlyPost, ReadOnlyComment)
- Add tests for immutable entity hydration, insert, update, delete
- Add tests for inline persist changes, relation graphs, mixed graphs
- Update FlatNum hydrator tests for lazy entity class resolution
- Remove duplicate testShouldNotExecuteEntityConstructorWhenDisabled
- Rename testMultipleFilteredCollectionsDontPersist to clarify intent
- Add actual refetch assertion to testReadOnlyDeleteAndRefetch

Author: alganet

src/Mapper.php

@@ -68,7 +68,7 @@ public function fetchAll(Collection $collection, mixed $extra = null): array
         return $entities;
     }
 
-    public function persist(object $object, Collection $onCollection): bool
+    public function persist(object $object, Collection $onCollection): object
     {
         if ($onCollection instanceof Filtered) {
             return parent::persist($object, $onCollection);

tests/Hydrators/FlatNumTest.php

@@ -39,7 +39,8 @@ public function hydrateSingleEntityFromNumericRow(): void
         $row = $stmt->fetch(PDO::FETCH_NUM);
 
         $hydrator = new FlatNum($stmt);
-        $result = $hydrator->hydrate($row, Collection::author(), $this->factory);
+        $collection = Collection::author();
+        $result = $hydrator->hydrate($row, $collection, $this->factory);
 
         $this->assertNotFalse($result);
         $this->assertCount(1, $result);
@@ -76,7 +77,8 @@ public function hydrateReturnsFalseForEmptyResult(): void
 
         $hydrator = new FlatNum($stmt);
 
-        $this->assertFalse($hydrator->hydrate($row, Collection::author(), $this->factory));
+        $collection = Collection::author();
+        $this->assertFalse($hydrator->hydrate($row, $collection, $this->factory));
     }
 
     #[Test]