Support PWA mode for mobile use

[lidel]

Some users may want to run this app as PWA on mobile and create an icon for quick access.

AFAIK all we need to do is to add some headers/manifests:

Manifest files are supported in Chrome, Edge, Firefox, UC Browser, Opera, and the Samsung browser. Safari has partial support

• https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps/Installable_PWAs
• https://web.dev/progressive-web-apps
  • https://web.dev/install-criteria/
  • https://web.dev/add-manifest/
• https://github.com/gokulkrishh/awesome-meta-and-manifest

Thoughts?

[jessicaschilling]

Small but useful. @rafaelramalho19 are you able to take this one today? 🙏