Fix OpenAI test using max_tokens for GPT-5 models

src-tauri/src/ai.rs

@@ -435,10 +435,12 @@ async fn test_anthropic(api_key: &str, model: &str) -> Result<String, String> {
 
 async fn test_openai(url: &str, api_key: Option<&str>, model: &str) -> Result<String, String> {
 	let client = Client::new();
+	let is_gpt5 = model.starts_with("gpt-5");
+	let token_key = if is_gpt5 { "max_completion_tokens" } else { "max_tokens" };
 
 	let body = json!({
 		"model": model,
-        "max_tokens": 10,
+		token_key: 10,
 		"messages": [
             {
                 "role": "user",