通知下拉菜单

Create a notification dropdown triggered by a bell icon in a navbar. Show an unread badge count on the bell. Inside the dropdown, display a list of notifications grouped by date (Today, Earlier) with icons, titles, timestamps, and read/unread states. Include "Mark all as read" and "View all" buttons at the bottom. Use shadcn/ui DropdownMenu, Button, and Badge components and Tailwind CSS. Make it keyboard accessible and responsive.

创建一个由导航栏铃铛图标触发的通知下拉菜单。铃铛上显示未读徽章数量。下拉菜单内按日期分组（Today、Earlier）显示通知列表，包含图标、标题、时间戳和已读/未读状态。底部包含 "全部标记为已读" 和 "查看全部" 按钮。使用 shadcn/ui DropdownMenu、Button 和 Badge 组件以及 Tailwind CSS。使其支持键盘访问并响应式。