feat: implement new layout components and routing structure

- Added HeaderLayout component for the application header.
- Introduced KeepAliveViewport for managing tab states and rendering.
- Created TabNav for tab navigation with animated indicator.
- Removed old Tabs component in favor of new layout structure.
- Updated routing with AppRouter and defined appTabs for navigation.
- Enhanced theme context to manage dark mode styles.
- Added new UI components: Badge, Button, Separator, and Tabs.
- Refactored pages to utilize new layout components and improve responsiveness.
- Updated global styles for better theming and layout consistency.
- Introduced TypeScript path aliases for cleaner imports.

frontend/src/components/shadcn/ui/button.tsx

@@ -0,0 +1,65 @@
+import * as React from 'react';
+import { cva, type VariantProps } from 'class-variance-authority';
+import { Slot } from 'radix-ui';
+
+import { cn } from '@/lib/utils';
+
+const buttonVariants = cva(
+  'group/button inline-flex shrink-0 items-center justify-center rounded-lg border border-transparent bg-clip-padding text-sm font-medium whitespace-nowrap transition-all outline-none select-none focus-visible:border-ring focus-visible:ring-3 focus-visible:ring-ring/50 active:not-aria-[haspopup]:translate-y-px disabled:pointer-events-none disabled:opacity-50 aria-invalid:border-destructive aria-invalid:ring-3 aria-invalid:ring-destructive/20 dark:aria-invalid:border-destructive/50 dark:aria-invalid:ring-destructive/40 [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*=size-])]:size-4',
+  {
+    variants: {
+      variant: {
+        default: 'bg-primary text-primary-foreground hover:bg-primary/90',
+        outline:
+          'border-border bg-background hover:bg-muted hover:text-foreground aria-expanded:bg-muted aria-expanded:text-foreground dark:bg-input/30 dark:hover:bg-input/50',
+        secondary:
+          'bg-secondary text-secondary-foreground hover:bg-secondary/80 aria-expanded:bg-secondary aria-expanded:text-secondary-foreground',
+        ghost:
+          'hover:bg-muted hover:text-foreground aria-expanded:bg-muted aria-expanded:text-foreground dark:hover:bg-muted/50',
+        destructive:
+          'bg-destructive/10 text-destructive hover:bg-destructive/20 focus-visible:border-destructive/40 focus-visible:ring-destructive/20 dark:bg-destructive/20 dark:hover:bg-destructive/30 dark:focus-visible:ring-destructive/40',
+        link: 'text-primary underline-offset-4 hover:underline',
+      },
+      size: {
+        default:
+          'h-8 gap-1.5 px-2.5 has-data-[icon=inline-end]:pr-2 has-data-[icon=inline-start]:pl-2',
+        xs: 'h-6 gap-1 rounded-[min(var(--radius-md),10px)] px-2 text-xs has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 [&_svg:not([class*=size-])]:size-3',
+        sm: 'h-7 gap-1 rounded-[min(var(--radius-md),12px)] px-2.5 text-[0.8rem] has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 [&_svg:not([class*=size-])]:size-3.5',
+        lg: 'h-9 gap-1.5 px-3 has-data-[icon=inline-end]:pr-2 has-data-[icon=inline-start]:pl-2',
+        icon: 'size-8',
+        'icon-xs': 'size-6 rounded-[min(var(--radius-md),10px)] [&_svg:not([class*=size-])]:size-3',
+        'icon-sm': 'size-7 rounded-[min(var(--radius-md),12px)]',
+        'icon-lg': 'size-9',
+      },
+    },
+    defaultVariants: {
+      variant: 'default',
+      size: 'default',
+    },
+  },
+);
+
+function Button({
+  className,
+  variant,
+  size,
+  asChild = false,
+  ...props
+}: React.ComponentProps<'button'> &
+  VariantProps<typeof buttonVariants> & {
+    asChild?: boolean;
+  }) {
+  const Comp = asChild ? Slot.Root : 'button';
+
+  return (
+    <Comp
+      data-slot="button"
+      data-variant={variant}
+      data-size={size}
+      className={cn(buttonVariants({ variant, size, className }))}
+      {...props}
+    />
+  );
+}
+
+export { Button };