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/routes/guards/guest-only.tsx

@@ -0,0 +1,13 @@
+import { Navigate, Outlet } from 'react-router-dom'
+
+import { useAuthStore } from '@/stores/auth-store'
+
+export const GuestOnly = () => {
+  const hasSession = useAuthStore((state) => Boolean(state.tokens))
+
+  if (hasSession) {
+    return <Navigate to="/dashboard" replace />
+  }
+
+  return <Outlet />
+}