feature request : offline signing

[peaceAndHodl]

Hi and thank you all contributors for the best eth wallet ever !

For people using key-store or not trusting ledger & co enough to plug them on an online device an option to sign offline would be paramount.

'export unsigned contract' (as file or qr code) 'import signed contract' 'broadcast' buttons under the contract waiting to be signed ?

So we can stay in watch wallet mode in frame and still interact with webapps.

(NB It is possible to sign offline with that old mycrypto wallet, but a cold frame version just to sign offline would be even more amazing to have !)