feat: initialize project with Symfony, React, and Tailwind CSS setup

- Add package.json with development and production dependencies
- Create postcss.config.js for Tailwind CSS integration
- Implement AdminController for handling admin routes
- Add admin index template with React root element
- Create base template for consistent layout
- Configure TypeScript with tsconfig.json
- Set up Webpack configuration for asset management

assets/admin/App.tsx

@@ -0,0 +1,43 @@
+import React from 'react';
+import { Routes, Route, Navigate } from 'react-router-dom';
+import { useAuthStore } from './stores/authStore';
+import AdminLayout from './components/layout/AdminLayout';
+import LoginPage from './pages/LoginPage';
+import DashboardPage from './pages/DashboardPage';
+
+function PrivateRoute({ children }: { children: React.ReactNode }) {
+  const isAuthenticated = useAuthStore((s) => s.isAuthenticated);
+  return isAuthenticated ? <>{children}</> : <Navigate to="/admin/login" replace />;
+}
+
+function PublicRoute({ children }: { children: React.ReactNode }) {
+  const isAuthenticated = useAuthStore((s) => s.isAuthenticated);
+  return isAuthenticated ? <Navigate to="/admin/dashboard" replace /> : <>{children}</>;
+}
+
+export default function App() {
+  return (
+    <Routes>
+      <Route
+        path="/admin/login"
+        element={
+          <PublicRoute>
+            <LoginPage />
+          </PublicRoute>
+        }
+      />
+      <Route
+        path="/admin/*"
+        element={
+          <PrivateRoute>
+            <AdminLayout />
+          </PrivateRoute>
+        }
+      >
+        <Route index element={<Navigate to="/admin/dashboard" replace />} />
+        <Route path="dashboard" element={<DashboardPage />} />
+      </Route>
+      <Route path="*" element={<Navigate to="/admin/dashboard" replace />} />
+    </Routes>
+  );
+}