feat: add iOS support and harden receipt scanning

app/ios/ScanReceipts/App/ScanReceiptsApp.swift

@@ -0,0 +1,23 @@
+import SwiftUI
+
+@main
+struct ScanReceiptsApp: App {
+    @StateObject private var appState = AppState()
+
+    init() {
+        // App-wide tint: the Zenith Silver system uses pure black for every
+        // interactive/structural accent (see Design/ZenithColors.swift) —
+        // there is no separate "brand blue" the way most iOS apps have one.
+        UITabBar.appearance().tintColor = UIColor(Color.zenithBlack)
+        UINavigationBar.appearance().tintColor = UIColor(Color.zenithBlack)
+    }
+
+    var body: some Scene {
+        WindowGroup {
+            RootView()
+                .environmentObject(appState)
+                .tint(.zenithBlack)
+                .task { await appState.bootstrap() }
+        }
+    }
+}