fix: remove thinkingConfig entirely — field does not exist in Gemini API

The API returned: Unknown name "thinkingConfig": Cannot find field.
gemini-2.5-flash works with a plain generateContent request, no special config needed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Services/GeminiVisionService.php

@@ -24,14 +24,10 @@ class GeminiVisionService
 
     private function buildRequest(array $contents, array $genConfig = []): array
     {
-        $body = [
+        return [
             'contents'         => $contents,
             'generationConfig' => array_merge(['temperature' => 0.1, 'maxOutputTokens' => 200], $genConfig),
         ];
-        if (preg_match('/gemini-(2\.5|3[\.\d]*)/', $this->model)) {
-            $body['thinkingConfig'] = ['thinkingBudget' => 0];
-        }
-        return $body;
     }
 
     /**