feat: 添加Gemini定价功能和界面优化

- 实现Gemini定价查询服务，支持实时计算token成本
- 改进API Key管理界面，添加模型快速选择功能
- 优化账户表单组件的渲染性能
- 更新Gemini账户服务，增强token刷新和错误处理

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/app.js

@@ -470,6 +470,14 @@ class Application {
         this.server.close(async () => {
           logger.info('🚪 HTTP server closed');
           
+          // 清理 pricing service 的文件监听器
+          try {
+            pricingService.cleanup();
+            logger.info('💰 Pricing service cleaned up');
+          } catch (error) {
+            logger.error('❌ Error cleaning up pricing service:', error);
+          }
+          
           try {
             await redis.disconnect();
             logger.info('👋 Redis disconnected');