fix: optimise throttle and hooks ...

In the process of fixing some hook dependencies, I introduced a bug
which caused the application to rapidly send requests to the Krist
server (luckily I was using a local Krist instance). To raise awareness
of this if it happens again in the future, I added a notification that
appears whenever the rate limit is hit. Ideally, it should never appear
in production.

feat: block difficulty card

feat: nyi warning

chore: update file headers

feat: support custom currencies

fix: sync node in redux

feat: add existing wallet button in create modal

fix: clear calculated address on modal close

feat: sync balances with websocket

fix: wallet action tooltip and corners

fix: minor add wallet improvements

feat: wallet editing

feat: wallet deletion

feat: show existing wallet categories

feat: wallet data syncing

feat: add wallets!

feat: hide advanced wallet formats

feat: add support for kw-username

fix: minor wallet modal tweaks

feat: mostly finish wallet dialogs

feat: initial work on wallet dialogs