feat: Divi read tools accept library entries (library access, E1/E3)

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

src/Integrations/WordPress/PostGuard.php

@@ -45,7 +45,7 @@ final class PostGuard
 
         $post = get_post($id);
         if (! $post instanceof WP_Post || ! $schema->isManaged((string) $post->post_type)) {
-            return Errors::notFound(sprintf('Eintrag %d nicht gefunden (oder kein unterstützter Inhaltstyp).', $id));
+            return self::notFound($id);
         }
 
         if (! current_user_can('edit_post', $id)) {
@@ -63,6 +63,12 @@ final class PostGuard
         return $post;
     }
 
+    /** The refusal for an ID that names no entry the tools manage – the same for every such ID. */
+    public static function notFound(int $id): WP_Error
+    {
+        return Errors::notFound(sprintf('Eintrag %d nicht gefunden (oder kein unterstützter Inhaltstyp).', $id));
+    }
+
     /**
      * A scheduled entry whose publication time has passed (WordPress' cron missed it) or is
      * less than a minute away: wp_insert_post() turns "future" into "publish" on any save when