feat: initialize frontend with Vite and PWA support

- Add index.html as the main entry point for the application.
- Create package.json to manage dependencies and scripts for development.
- Include favicon.svg for the application icon.
- Configure PWA assets generation with pwa-assets.config.js.
- Implement counter functionality in counter.js with notification on reaching 5.
- Add JavaScript logo SVG for branding.
- Set up main.js to render the application and handle user interactions.
- Create notification.js to manage browser notifications.
- Implement PWA registration and update handling in pwa.js.
- Style the application with a new style.css file.
- Configure Vite with PWA plugin in vite.config.js for service worker and manifest settings.

backend/src/config/database.ts

@@ -0,0 +1,9 @@
+export default {
+  uri: process.env.MONGODB_URI || 'mongodb://localhost:27017',
+  dbName: process.env.MONGODB_DB_NAME || 'budget-manager',
+  collections: {
+    users: 'users',
+    transactions: 'transactions',
+    categories: 'categories'
+  }
+};