New post error fix (#2)

* refactor: update invalidateCache signature to int|string|null

* Update CacheInvalidator.php

Author: digital-brew

src/Services/CacheInvalidator.php

@@ -38,7 +38,7 @@ protected function registerHooks(): void
         add_action('deleted_term', [$this, 'invalidateCache']);
     }
 
-    public function invalidateCache(?int $postId = null): void
+    public function invalidateCache(int|string|null $postId = null): void
     {
         // Only invalidate for configured post types
         if ($postId && ! $this->shouldInvalidateForPost($postId)) {
@@ -71,7 +71,7 @@ public function handleMetaDelete(array $metaIds, int $postId): void
         $this->invalidateCache($postId);
     }
 
-    protected function shouldInvalidateForPost(int $postId): bool
+    protected function shouldInvalidateForPost(int|string $postId): bool
     {
         $postType = get_post_type($postId);
         $configuredTypes = config('llms-txt.post_types', ['post', 'page']);