Replace the silent (long) cast with an explicit fractional check:
if value * factor has a non-zero remainder, TryParseIn/TryParseCoins
return false. The caller already shows "Importo non valido." to the
user, so no UI change is needed.
Covers TryParseIn (all units) and TryParseCoins. Adds CoinAmountTests
with valid and invalid cases including the triggering example (1.9 sat).
Add global AppConfig (config.json, blueprint §8) persisting language
and amount unit. CoinAmount gains unit-aware formatting and parsing
(PLM, mPLM, µPLM, sat), applied everywhere amounts are shown or
entered, including the send form. New Loc i18n layer (it/en) with
live-updating XAML bindings covering menu, wizard, wallet panel and
status messages.
The Impostazioni menu opens a dropdown with separate Lingua and Unità
entries (radio-checked submenus, applied and saved on click), ready to
host future settings.
davide