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/app.js

@@ -0,0 +1,13 @@
+import { registerReactControllerComponents } from '@symfony/ux-react';
+import './stimulus_bootstrap.js';
+/*
+ * Welcome to your app's main JavaScript file!
+ *
+ * We recommend including the built version of this JavaScript file
+ * (and its CSS file) in your base layout (base.html.twig).
+ */
+
+// any CSS you import will output into a single css file (app.css in this case)
+import './styles/app.css';
+
+registerReactControllerComponents(require.context('./react/controllers', true, /\.(j|t)sx?$/));