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/models/index.ts

@@ -0,0 +1,33 @@
+import { ObjectId } from 'mongodb';
+
+export interface User {
+  _id?: ObjectId;
+  username: string;
+  password: string;
+  email?: string;
+  role?: 'user' | 'admin';
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface Transaction {
+  _id?: ObjectId;
+  userId: ObjectId;
+  amount: number;
+  type: 'income' | 'expense';
+  categoryId: ObjectId;
+  description: string;
+  date: Date;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface Category {
+  _id?: ObjectId;
+  name: string;
+  userId: ObjectId;
+  icon?: string;
+  color?: string;
+  createdAt: Date;
+  updatedAt: Date;
+}