Change the default model to qwen3-max to mitigate output quality issues caused by model downgrading.

mcp/client.go

@@ -81,7 +81,7 @@ func (client *Client) SetQwenAPIKey(apiKey string, customURL string, customModel
 		client.Model = customModel
 		log.Printf("🔧 [MCP] Qwen 使用自定义 Model: %s", customModel)
 	} else {
-		client.Model = "qwen-plus" // 可选: qwen-turbo, qwen-plus, qwen-max
+		client.Model = "qwen3-max" 
 		log.Printf("🔧 [MCP] Qwen 使用默认 Model: %s", client.Model)
 	}
 	// 打印 API Key 的前后各4位用于验证