text: Title: Web app manifest for assistant website
  Body: I'd like to suggest that you add a web app manifest to the assistant website. 
  
  https://developer.mozilla.org/en-US/docs/Web/Manifest
  https://web.dev/add-manifest/
  
  With the correct settings (`"display": "standalone"`), this will enable users (using Chrome, Edge or Safari) to "Install" the assistant on mobile devices or desktop so that it appears nearly like a native app.