Quick Bug fix release

• UI: rewrite add button dropdown, avoid context menu click cause menu hide
• UI: Fix some theme detail issue
• UI: Improve system sub menu UI
• UI: improve close tab button color
• UI: lazy load sftp component to avoid app freeze

快速问题修复

• UI: 重写添加按钮下拉菜单，避免上下文菜单点击导致菜单隐藏
• UI: 修复主题渲染跟之前不一致问题
• UI: 改进系统菜单界面
• UI: 改进标签页关闭按钮颜色
• UI: 延迟加载sftp组件避免卡顿