Implement PWA features

[adeebshihadeh]

This issue is for making this a complete PWA, including but not limited to:

• icons
• splash screen
• a defined offline mode (doesn't have to do anything, except say "connect offline")

As well as testing the PWA-ness in CI.

[adeebshihadeh]

This looks interesting https://github.com/elegantapp/pwa-asset-generator

[seanaguinaga]

How's this: https://github.com/commaai/new-connect/pull/68

Oops need to add CI - standby

[griffinbaker12]

Just a thought on the design for the exit screen I was working on:

The asset generator linked above also integrates really well with the rest of the project. I ran:

npx pwa-asset-generator ./public/images/icon-vector.svg ./temp -b "#141414" -m public/manifest.json -i ./index.html

to make sure the app's bg on the phone screen matched that of the svg icon.

If helpful, you can find the approach I was taking here.