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>

src/Integrations/Divi/DiviIntegration.php

@@ -100,15 +100,7 @@ final class DiviIntegration implements Integration
     public function abilities(): array
     {
         $loader = $this->loader();
-        $composition = new DiviComposition($this->modules, $this->design);
-        $writer = new DiviWriter(
-            $loader,
-            new DiviSaver(),
-            $this->log,
-            $this->design,
-            $composition,
-            new GlobalEdits($this->access, new GlobalUsages())
-        );
+        $writer = $this->writer($loader);
 
         return [
             new DiviOutlineAbility($loader, $this->design),
@@ -127,7 +119,29 @@ final class DiviIntegration implements Integration
     /** The group "Divi-Bibliothek" (lit/library-*), sharing this integration's library access. */
     public function library(): LibraryIntegration
     {
-        return new LibraryIntegration($this->access, $this->loader(), $this->design);
+        $loader = $this->loader();
+
+        return new LibraryIntegration(
+            $this->access,
+            $loader,
+            $this->design,
+            $this->writer($loader),
+            new DiviSaver(),
+            $this->log,
+            $this->modules
+        );
+    }
+
+    private function writer(DiviPageLoader $loader): DiviWriter
+    {
+        return new DiviWriter(
+            $loader,
+            new DiviSaver(),
+            $this->log,
+            $this->design,
+            new DiviComposition($this->modules, $this->design),
+            new GlobalEdits($this->access, new GlobalUsages())
+        );
     }
 
     private function loader(): DiviPageLoader