feat: add gpt-5 support (#1105)

* feat: add gpt-5 support

src/ai-providers/openai.js

@@ -20,6 +20,16 @@ export class OpenAIProvider extends BaseAIProvider {
 		return 'OPENAI_API_KEY';
 	}
 
+	/**
+	 * Determines if a model requires max_completion_tokens instead of maxTokens
+	 * GPT-5 models require max_completion_tokens parameter
+	 * @param {string} modelId - The model ID to check
+	 * @returns {boolean} True if the model requires max_completion_tokens
+	 */
+	requiresMaxCompletionTokens(modelId) {
+		return modelId && modelId.startsWith('gpt-5');
+	}
+
 	/**
 	 * Creates and returns an OpenAI client instance.
 	 * @param {object} params - Parameters for client initialization