feature #50 feat: Google structured output (valtzu)

This PR was merged into the main branch.

Discussion
----------

feat: Google structured output

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Docs?         | no
| Issues        |
| License       | MIT

Cherry picking php-llm/llm-chain#354

Commits
-------

0a0e632 feat: Google structured output (#354)

Author: OskarStark

src/Bridge/Google/Gemini.php

@@ -36,6 +36,7 @@ public function __construct(string $name = self::GEMINI_2_PRO, array $options =
             Capability::INPUT_AUDIO,
             Capability::INPUT_PDF,
             Capability::OUTPUT_STREAMING,
+            Capability::OUTPUT_STRUCTURED,
             Capability::TOOL_CALLING,
         ];
 

src/Bridge/Google/ModelHandler.php

@@ -61,6 +61,12 @@ public function request(Model $model, array|string $payload, array $options = []
             $options['stream'] ?? false ? 'streamGenerateContent' : 'generateContent',
         );
 
+        if (isset($options['response_format']['json_schema']['schema'])) {
+            $options['responseMimeType'] = 'application/json';
+            $options['responseJsonSchema'] = $options['response_format']['json_schema']['schema'];
+            unset($options['response_format']);
+        }
+
         $generationConfig = ['generationConfig' => $options];
         unset($generationConfig['generationConfig']['stream']);
         unset($generationConfig['generationConfig']['tools']);