fix: lit/divi-node-copy from a library entry needs the insert rights (I-1, L5)

A library entry as source now requires LibraryAccess::canInsert() (add_library,
writable library group) and follows lit-library-insert's Tools-tab state
(disabled -> unsupported). DiviPageLoader::library() gets its caller.

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

src/Plugin.php

@@ -89,12 +89,19 @@ final class Plugin
         $libraryWritable = static function () use (&$policy): bool {
             return $policy instanceof ExposurePolicy && $policy->groupWritable(LibraryAccess::GROUP);
         };
+        // Audit L5: lit/divi-node-copy from a library entry follows lit/library-insert's Tools-tab state.
+        $libraryInsertable = static function () use (&$registry, &$policy): bool {
+            return $registry instanceof IntegrationRegistry
+                && $policy instanceof ExposurePolicy
+                && $policy->allows('lit/library-insert', $registry->abilities());
+        };
         $divi = new DiviIntegration(
             $schema,
             $changeLog,
             $libraryWritable,
             libraryVisible: $libraryVisible,
-            diviWritable: $diviWritable
+            diviWritable: $diviWritable,
+            libraryInsertable: $libraryInsertable
         );
         $registry = new IntegrationRegistry(
             new CoreIntegration(self::pluginDir() . '/docs/guides'),