feat: add initial implementation of Kitchen CRM with authentication and dashboard features

- Create global styles and theme management
- Implement app shell layout with sidebar navigation
- Add authentication layout and pages for login and registration
- Develop dashboard page with placeholder content
- Introduce routing guards for guest-only and authenticated routes
- Set up Zustand for state management of authentication and theme
- Create API types and structures for CRM entities
- Configure Vite with PWA support and Tailwind CSS

frontend/src/components/ui/input.tsx

@@ -0,0 +1,22 @@
+import * as React from 'react'
+
+import { cn } from '@/lib/utils'
+
+export interface InputProps extends React.InputHTMLAttributes<HTMLInputElement> {}
+
+const Input = React.forwardRef<HTMLInputElement, InputProps>(({ className, type, ...props }, ref) => {
+  return (
+    <input
+      type={type}
+      className={cn(
+        'flex h-10 w-full rounded-md border border-input bg-transparent px-3 py-2 text-sm shadow-sm transition-colors file:border-0 file:bg-transparent file:text-sm file:font-medium placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50',
+        className,
+      )}
+      ref={ref}
+      {...props}
+    />
+  )
+})
+Input.displayName = 'Input'
+
+export { Input }