fix agent stub

Author: ilvalerione

src/Agent/ChatHistoryHelper.php

@@ -11,7 +11,6 @@
 use NeuronAI\Observability\Events\MessageSaving;
 
 use function is_array;
-use function spl_object_hash;
 
 trait ChatHistoryHelper
 {

src/Agent/Middleware/Summarization.php

@@ -289,7 +289,7 @@ protected function countTokens(array $messages): int
             } else {
                 // Estimate tokens (rough approximation: 1 token ≈ 4 characters)
                 $contentStr = $message->getContent();
-                $totalTokens += (int) ceil(mb_strlen($contentStr) / 4);
+                $totalTokens += (int) ceil(mb_strlen((string) $contentStr) / 4);
             }
         }
 

src/Providers/Gemini/HandleStructured.php

@@ -6,9 +6,9 @@
 
 use NeuronAI\Chat\Enums\MessageRole;
 use NeuronAI\Chat\Messages\Message;
-
 use NeuronAI\Exceptions\HttpException;
 use NeuronAI\Exceptions\ProviderException;
+
 use function array_key_exists;
 use function end;
 use function is_array;