feat: add sidebar component with context and mobile support

- Implemented Sidebar component with collapsible functionality.
- Added SidebarProvider for managing open state and keyboard shortcuts.
- Created SidebarTrigger, SidebarRail, and various sidebar elements (Header, Footer, Content, etc.).
- Integrated mobile responsiveness using Sheet component.
- Added utility hooks for mobile detection.

feat: create table component for structured data display

- Developed Table component with subcomponents: TableHeader, TableBody, TableFooter, TableRow, TableCell, and TableCaption.
- Enhanced styling for better readability and usability.

feat: implement tabs component for navigation

- Created Tabs component with TabsList, TabsTrigger, and TabsContent for tabbed navigation.
- Ensured accessibility and responsive design.

feat: add toggle group component for grouped toggle buttons

- Developed ToggleGroup and ToggleGroupItem components for managing toggle states.
- Integrated context for consistent styling and behavior.

feat: create toggle component for binary state representation

- Implemented Toggle component with variant and size options.
- Enhanced user interaction with visual feedback.

feat: add tooltip component for contextual information

- Developed Tooltip, TooltipTrigger, and TooltipContent for displaying additional information on hover.
- Integrated animations for a smoother user experience.

feat: implement mobile detection hook

- Created useIsMobile hook to determine if the user is on a mobile device.
- Utilized matchMedia for responsive design adjustments.

web/src/components/user/user-header.tsx

@@ -16,7 +16,7 @@ export function UserHeader({ user }: { user: User }) {
 
       {/* 右侧 70%（信息区） */}
       <div className="md:basis-[70%] p-4 flex flex-col justify-center space-y-2">
-        <h2 className="text-2xl font-bold mt-0">{user.nickname}</h2>
+        <h2 className="text-2xl font-bold mt-0">{user.nickname || user.username || '未填写昵称'}</h2>
         <p className="text-gray-500 dark:text-gray-400 mt-1">@{user.username}</p>
 
         <div className="flex items-center text-sm text-slate-600 dark:text-slate-400">