Add service worker logic and site manifest

[Spomky]

This PR adds a new service worker and the site manifest for enhancing the application's caching strategies and PWA (Progressive Web App) features. New files were created for the service worker, the manifest file, and several other JavaScript files relating to Workbox libraries. The service worker uses these libraries to handle static content caching, clearing outdated cache, default network-only strategy, triggering cache updates, and to control UI.