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/services/database.ts

@@ -0,0 +1,46 @@
+import { Collection, Db, MongoClient, type Document } from 'mongodb';
+import dbConfig from '../config/database';
+
+class DatabaseService {
+    private client: MongoClient;
+    private db: Db | null = null;
+    private static instance: DatabaseService;
+
+    private constructor() {
+        this.client = new MongoClient(dbConfig.uri);
+    }
+
+    static getInstance(): DatabaseService {
+        if (!DatabaseService.instance) {
+            DatabaseService.instance = new DatabaseService();
+        }
+        return DatabaseService.instance;
+    }
+
+    async connect(): Promise<void> {
+        try {
+            await this.client.connect();
+            this.db = this.client.db(dbConfig.dbName);
+            console.log('Connected to MongoDB successfully');
+        } catch (error) {
+            console.error('Failed to connect to MongoDB', error);
+            throw error;
+        }
+    }
+
+    getCollection<T extends Document>(collectionName: string): Collection<T> {
+        if (!this.db) {
+            throw new Error('Database connection not established. Call connect() first.');
+        }
+        return this.db.collection<T>(collectionName);
+    }
+
+    async disconnect(): Promise<void> {
+        if (this.client) {
+            await this.client.close();
+            console.log('Disconnected from MongoDB');
+        }
+    }
+}
+
+export default DatabaseService;