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

postcss.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  plugins: {
+    '@tailwindcss/postcss': {},
+  },
+};