Marina as PWA

[tiero]

I will write a more extended proposal version for now TL;DR

• Chrome Store banned us and Firefox still not supports properly manifest v3 and service workers.
• The unfair advantage of marina as extensions is injecting window.marina (or. window.liquid). Thta promise does not seems what the current users of Liquid really look for or need (as we dont have much concept of Dapps etc.)

We could then start adding Bitcoin mainchain (Silent Payments?) and release it as PWA with minimal code changes (as is already a mobile responsive design, we may need to review the onboarding screens)

[Impa10r]

I managed to install into Opera in Developer mode, and it works fine (playing on testnet).