Rewritten from the ground up as a Kotlin Multiplatform app - same features, now with a shared codebase across platforms.

New:
- Country flag emoji next to each currency code, where available
- Support for precious metals (gold, silver, platinum, palladium) alongside fiat currencies
- Search in the currency picker, with results also matching issuing country names
- Currency picker now splits selections into Priced/Unpriced
- Reset button to clear all selected currencies (with confirmation)
- "1 currency to Sats" field, editable directly for Manual price sources
- Move currencies to the top or bottom of the list

Improved:
- Manual price source: simplified UI, seeded from another source, editable rate
- Selected currencies, exchange rates, and price source now persist between launches
- Locale-aware number formatting (digit grouping) and human-readable "updated" timestamps
- More accurate currency list: withdrawn/superseded currency codes filtered out