fix for issue #4 feat: add PWA support, service-worker, masked icon

[theonly1me]

Fix for Issue #4 : add PWA support, service-worker, masked icon

Description

• Update manifest to include masked icon for iOS and Android
• Update index.html to add manifest
• Add service-worker, using a Network First StaleWhileRevalidate policy
• Add serviceWorkerRegistration helper to register service-worker in 'prod' environment

Related Issue
Fix #4

@bjarneo the Hemmelig.app can now be used as a PWA, here are the details of the functionality that has been added:

• Users will be able to see cached app in case of network connectivity failure
• The Add to home screen prompt appears on Android devices (screenshot below from my testing)
• Unfortunately, iPhones do not allow a prompt since Apple has restricted that behavior. However, users will still be able to click the Share button on 'Safari' and click add to Home Screen to add the PWA to their home screen.
• Since the service-worker only kicks in in the production environment, I have deployed the UI on netlify at https://pwa.atchyut.dev and enabled SSL so that it can be tested via mobile devices and tablets. (Please Note: I will be deleting this deployment from Netlify once you test it from your end and are good with the functionality)

Add to Home Screen Prompt on Android:

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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[theonly1me]

@bjarneo Oh and the Sign In button gets hidden behind the Sign Up button on mobile devices. I've seen this happen on iPhone 12 Mini, iPhone SE 2020 and Samsung Galaxy s9. So that probably needs fixing too 😄

[bjarneo]

Looks good to me, but I have a few questions :)

[bjarneo]

@bjarneo Oh and the Sign In button gets hidden behind the Sign Up button on mobile devices. I've seen this happen on iPhone 12 Mini, iPhone SE 2020 and Samsung Galaxy s9. So that probably needs fixing too 😄

You are correct. Here is an issue for this :) #105

Thanks for this PR!

[bjarneo]

Let's go!

[bjarneo]

Updated the PR with hacktoberfest-accepted, @theonly1me

[theonly1me]

thanks a lot @bjarneo