Add cerebras platform configuration option

Author: muqeetsyed

src/ai-bundle/config/options.php

@@ -76,6 +76,11 @@
                         ->scalarNode('host_url')->defaultValue('http://127.0.0.1:11434')->end()
                         ->end()
                     ->end()
+                    ->arrayNode('cerebras')
+                        ->children()
+                        ->scalarNode('api_key')->isRequired()->end()
+                        ->end()
+                    ->end()
                 ->end()
             ->end()
             ->arrayNode('agent')

src/ai-bundle/tests/DependencyInjection/AiBundleTest.php

@@ -323,6 +323,9 @@ private function getFullConfig(): array
                     'ollama' => [
                         'host_url' => 'http://127.0.0.1:11434',
                     ],
+                    'cerebras' => [
+                        'api_key' => 'cerebras_key_full',
+                    ],
                 ],
                 'agent' => [
                     'my_chat_agent' => [