feat: lit/library-save creates library entries like Divi (E4)

Reuses NewDraft for insert and rollback (P6), requires edit_global_library
for scope global (P7), refuses opaque and global roots before wrapping (P11)
and checks the node with StoredNodeGuard. The source page is never written.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/Unit/Integrations/WordPress/Content/NewDraftTest.php

@@ -62,4 +62,26 @@ final class NewDraftTest extends TestCase
             self::assertSame(NewDraft::REASON_EXTRAS, $e->reason);
         }
     }
+
+    /** lit/library-save reuses the transaction without a PostWriter and names its entry (ruling P6). */
+    public function testWithoutAWriterOnlyTheEntryIsDeletedAndPartialsNameTheEntry(): void
+    {
+        Functions\when('wp_delete_post')->justReturn(false);
+        $log = FakeChangeLog::partialsOnly();
+        $draft = new NewDraft(null, $log, 'lit/library-save', 'et_pb_layout', 'Bibliothekseintrag');
+
+        try {
+            $draft->discard(2001, new RuntimeException('layout kaputt'), 'Grund.');
+            self::fail('WriteFailed expected');
+        } catch (WriteFailed $e) {
+            self::assertFalse($e->rolledBack);
+            self::assertSame(2001, $e->postId);
+        }
+        $log->assertPartials([
+            'ability' => 'lit/library-save',
+            'object_type' => 'et_pb_layout',
+            'object_id' => '2001',
+            'summary' => 'Bibliothekseintrag 2001: Anlegen nur teilweise zurückgenommen',
+        ]);
+    }
 }