Improve display on big screens

[MrStahlfelge]

The app is not optimized for big screens like tablets or Chromebooks (or Windows 11) at the moment.
It should be improved in a way that does not impose any more overhead to development because big screens aren't used frequently compared to phones, so we don't want to change the navigation flow.

Quick win changes that improve the experience on big screens:

• Wallet list screen: Don't place the wallet cards vertical, but in a grid (like Google Keep or Photos app)
• Wallet details: Show the screen in two coloumns with the transaction list on the right hand side, all other information on the left hand side
• Transaction info (ErgoPay Signing, Cold wallet signing, transaction details): two-column layout
• All other screens: Make sure that the content has a max width size and is centered horizontally.