Add a Reset button to clear selected currencies, with confirmation

New "Reset" button in the currency picker's top bar (next to Done),
shown only when more than the pinned default currency is selected.
Tapping it asks for confirmation before removing every other
selected currency, via PriceViewModel.onSelectedCurrenciesReset() —
same recompute/persist pattern as onFiatCurrencyToggled.

Compose uses an AlertDialog; iOS/macOS uses .alert with a destructive
Reset action, matching the destructive-role toolbar button that
triggers it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FXcrACM5sok3M1KQJ8kByy

iosApp/iosApp/ContentView.swift

@@ -238,7 +238,9 @@ struct ContentView: View {
                 pricedCurrencyCodes: state.pricedCurrencyCodes,
                 sourceName: state.sourceName,
                 localeCurrencyCode: state.localeCurrencyCode,
-                onToggle: { viewModel.onFiatCurrencyToggled($0) }
+                selectedCount: state.selectedCurrencyCodes.count,
+                onToggle: { viewModel.onFiatCurrencyToggled($0) },
+                onReset: { viewModel.onSelectedCurrenciesReset() }
             )
         }
         .environment(\.openURL, OpenURLAction { url in

iosApp/iosApp/ConverterViewModel.swift

@@ -39,6 +39,10 @@ final class ConverterViewModel: ObservableObject {
         bridge.onFiatCurrenciesReordered(newOrder: newOrder)
     }
 
+    func onSelectedCurrenciesReset() {
+        bridge.onSelectedCurrenciesReset()
+    }
+
     func onSourceSelected(_ name: String) {
         bridge.onSourceSelected(name: name)
     }

iosApp/iosApp/CurrencyPickerSheet.swift

@@ -8,10 +8,13 @@ struct CurrencyPickerSheet: View {
     let pricedCurrencyCodes: [String]
     let sourceName: String
     let localeCurrencyCode: String?
+    let selectedCount: Int
     let onToggle: (String) -> Void
+    let onReset: () -> Void
 
     @Environment(\.dismiss) private var dismiss
     @State private var searchQuery = ""
+    @State private var showResetConfirmation = false
 
     private func matches(_ info: CurrencyInfo) -> Bool {
         SystemCurrenciesKt.matchesCurrencySearch(info: info, query: searchQuery)
@@ -60,6 +63,16 @@ struct CurrencyPickerSheet: View {
             .navigationBarTitleDisplayMode(.inline)
             #endif
             .toolbar {
+                if selectedCount > 1 {
+                    ToolbarItem(placement: .cancellationAction) {
+                        Button(
+                            IosLocalizationKt.localizedString(resource: MR.strings.shared.reset_selected_currencies_button),
+                            role: .destructive
+                        ) {
+                            showResetConfirmation = true
+                        }
+                    }
+                }
                 ToolbarItem(placement: .confirmationAction) {
                     Button(IosLocalizationKt.localizedString(resource: MR.strings.shared.done)) { dismiss() }
                 }
@@ -74,6 +87,23 @@ struct CurrencyPickerSheet: View {
             text: $searchQuery,
             prompt: IosLocalizationKt.localizedString(resource: MR.strings.shared.search_currencies_placeholder)
         )
+        .alert(
+            IosLocalizationKt.localizedString(resource: MR.strings.shared.reset_selected_currencies_confirmation_title),
+            isPresented: $showResetConfirmation
+        ) {
+            Button(
+                IosLocalizationKt.localizedString(resource: MR.strings.shared.reset_selected_currencies_button),
+                role: .destructive
+            ) {
+                onReset()
+            }
+            Button(IosLocalizationKt.localizedString(resource: MR.strings.shared.cancel), role: .cancel) {}
+        } message: {
+            Text(IosLocalizationKt.localizedFormattedString(
+                resource: MR.strings.shared.reset_selected_currencies_confirmation_message,
+                args: [currentCurrency.code]
+            ))
+        }
         #if os(macOS)
         // macOS sizes a .sheet() to its content's ideal size rather than the parent window's
         // size (unlike iOS, which presents modally full-size); without an explicit frame here,