feat(config): 添加 OpenAPI 配置类

- 新增 OpenApiConfig 类，配置 Swagger 文档信息
- 定义 API 文档的标题、描述和版本号

trading_platform/src/main/java/com/trading_platform/config/OpenApiConfig.java

@@ -0,0 +1,19 @@
+package com.trading_platform.config;
+
+import io.swagger.v3.oas.models.OpenAPI;
+import io.swagger.v3.oas.models.info.Info;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class OpenApiConfig {
+
+    @Bean
+    public OpenAPI customOpenAPI() {
+        return new OpenAPI()
+                .info(new Info()
+                        .title("Trading Platform API 文档")
+                        .description("swagger 文档 by 13")
+                        .version("1.0."));
+    }
+}