feat: lit-library-insert as copy or global instance in the builder's format (E5)

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

src/Integrations/Divi/Library/LibraryAccess.php

@@ -148,6 +148,16 @@ class LibraryAccess
         return $this->roles->refusal('edit_global_library');
     }
 
+    /**
+     * Inserting from the library into a page (E3): canList(), the role option add_library (Divi's
+     * "Aus der Bibliothek hinzufügen") and a group "Divi-Bibliothek" that is not read-only or
+     * disabled (E9). Reading the entry itself stays item() (ruling P5).
+     */
+    public function canInsert(): ?WP_Error
+    {
+        return $this->canList() ?? $this->roles->refusal('add_library') ?? $this->writableGate();
+    }
+
     /** Refusal while the Tools tab keeps this connection from writing to the library. */
     public function writableGate(): ?WP_Error
     {