- modify webmanifest to use LNBITS_SITE_TITLE and LNBITS_CUSTOM_LOGO env vars
- modify webmanifest to have a more accurate description, start_url and set theme_color to match default lnbits theme
- add service worker to cache requests (chrome requires a registered service worker to activate some pwa functionality)
- move webmanifest to <head> (chrome acts weird with it in the body)