Offline PWA: Save generated QR-Code locally

[Dominic-Marcelino]

Allow users to save the generated qr-codes locally in their browser.

• add PWA support (vite PWA)[https://github.com/antfu/vite-plugin-pwa]
• Add option to store input / output in Localstorage
• List and load from local storage
• Generate PWA icons
  -->(public/image/icons)
• Load PWA icons