fix: S40 - short form and attrs on the same path refused for new nodes too

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

tests/Unit/Integrations/Divi/Pages/DiviWriteAbilitiesTest.php

@@ -278,6 +278,25 @@ final class DiviWriteAbilitiesTest extends TestCase
         self::assertSame([], $this->saved);
     }
 
+    /** Ruling S40: the S38 overlap rule for new nodes too. */
+    public function testInsertRefusesShortFormAndAttrsOnTheSamePath(): void
+    {
+        $result = $this->insert()->execute([
+            'post_id' => 7,
+            'tree_rev' => $this->treeRev(),
+            'parent' => 's0.r0.c1',
+            'nodes' => [[
+                'type' => 'button',
+                'text' => 'Neu',
+                'attrs' => ['button.innerContent' => ['desktop' => ['linkUrl' => '/neu']]],
+            ]],
+        ]);
+
+        self::assertSame('lit_validation_failed', $result->get_error_code());
+        self::assertArrayHasKey('nodes[0].attrs.button.innerContent', self::clientError($result)['fields']);
+        self::assertSame([], $this->saved);
+    }
+
     /** Ruling S7: builder-only paths are refused for users without unfiltered_html – visible to the client. */
     public function testBuilderOnlyPathsAreRefusedForEditors(): void
     {