v5.0 - Pick any of 126 currencies.

* The new "Other currency" option opens a picker of 126 fiat
  currencies, discovered from the backend catalog and cached for
  offline use so the list shows up instantly.
* Every currency now gets the full treatment — 24h sparkline and 7d
  change — via the parameterised price feed, not just USD and EUR.
* Quick-picks for US Dollars, Euros, Bitcoin, Sats, and Block height
  stay one tap away.
