feat: PWA

[qwerzl]

We do need a proper PWA support. We wont't pay $100 tax to Apple.

• Initial PWA support

Richer installation UI

• Description
• Screenshots

Native integration

• Maskable icon
• Monochrome Icon (Useful for Android phones with Monet icons; implemented by W3C but not yet implemented by browsers)
• Dynamic theme_color and background_color (Still not implemented by W3C)