feat: initialize frontend with React, Vite, and Tailwind CSS

- Added package.json for project dependencies and scripts.
- Configured PostCSS with Tailwind CSS.
- Created main application structure with App component and routing.
- Implemented API client for handling requests with Axios.
- Developed authentication API for login, logout, and user verification.
- Created entities API for managing virtual entities.
- Implemented logs API for fetching dispatch logs.
- Added navigation bar component for app navigation.
- Created protected route component for route guarding.
- Set up global CSS with Tailwind directives.
- Configured main entry point for React application.
- Developed basic Dashboard and Login pages.
- Set up router for application navigation.
- Added Jest testing setup for testing library.
- Configured Tailwind CSS with content paths.
- Set TypeScript configuration for frontend.
- Created Vite configuration for development and production builds.
- Added Nginx configuration for serving the application and proxying API requests.

frontend/src/components/NavBar.tsx

@@ -0,0 +1,29 @@
+import { Link, useLocation } from 'react-router-dom'
+
+const NAV_LINKS = [
+  { to: '/', label: 'Dashboard' },
+  { to: '/entities', label: 'Entities' },
+  { to: '/logs', label: 'Logs' },
+]
+
+/** Top navigation bar for authenticated pages. */
+export default function NavBar() {
+  const { pathname } = useLocation()
+
+  return (
+    <nav className="border-b bg-white">
+      <div className="mx-auto flex max-w-7xl items-center gap-6 px-4 py-3">
+        <span className="font-semibold text-gray-900">Condado SA</span>
+        {NAV_LINKS.map(({ to, label }) => (
+          <Link
+            key={to}
+            to={to}
+            className={`text-sm ${pathname === to ? 'font-semibold text-blue-600' : 'text-gray-600 hover:text-gray-900'}`}
+          >
+            {label}
+          </Link>
+        ))}
+      </div>
+    </nav>
+  )
+}

frontend/src/components/ProtectedRoute.tsx

@@ -0,0 +1,22 @@
+import { type ReactNode } from 'react'
+import { Navigate } from 'react-router-dom'
+import { useQuery } from '@tanstack/react-query'
+import { getMe } from '../api/authApi'
+
+interface ProtectedRouteProps {
+  children: ReactNode
+}
+
+/** Redirects to /login if the current JWT session is not valid. */
+export default function ProtectedRoute({ children }: ProtectedRouteProps) {
+  const { data, isLoading, isError } = useQuery({
+    queryKey: ['auth', 'me'],
+    queryFn: getMe,
+    retry: false,
+  })
+
+  if (isLoading) return <div>Loading...</div>
+  if (isError || !data) return <Navigate to="/login" replace />
+
+  return <>{children}</>
+}