german localization for in-app messages

STUB

• add german translations for commands and messages
• bonus: establish process for updating them as they change

see:

• https://0xacab.org/team-friendo/signalboost/blob/master/app/services/dispatcher/strings/commands/EN.js
• https://0xacab.org/team-friendo/signalboost/blob/master/app/services/dispatcher/strings/messages/EN.js

out of scope

• CLI localization and docs. would be awesome but feels less urgent?
• in any case, there's a card for that too! #79