Add "Progressive Web App (PWA)" support

This pull request introduces crucial updates aimed at optimizing our web application's functionality as a Progressive Web App (PWA). The following enhancements have been implemented: 1. **Manifest Integration**: Added `manifest.json` to enable a seamless installation experience and ensure an app-like feel across various devices and platforms. The manifest file includes metadata such as app name, description, version, start URL, display mode (`standalone`), background color, theme color, and multiple icon sizes optimized for different contexts. 2. **Service Worker Implementation**: Introduced `service-worker.js` to enhance offline capabilities, caching strategies, and overall performance. Key features include: - **Installation**: Precaching essential resources (`main.ts`, `favicon.ico`, `icon.png`) upon service worker installation to improve initial load times and offline access. - **Fetch Handling**: Intercepts fetch requests to serve cached responses when available, or fetch from the network and cache new responses for subsequent visits. - **Activation**: Ensures the service worker activates correctly and manages cache cleanup to maintain optimal performance over time. These updates are designed to significantly enhance usability, responsiveness, and reliability of our web application, aligning it with industry best practices for Progressive Web Apps.