feat: add iOS support and harden receipt scanning

app/ios/ScanReceipts/App/RootView.swift

@@ -0,0 +1,38 @@
+import SwiftUI
+
+/// Top-level router: which screen the user sees is entirely a function of
+/// `AppState.phase`. Nothing else in the app should make navigation
+/// decisions based on auth state — route through here instead.
+struct RootView: View {
+    @EnvironmentObject private var appState: AppState
+
+    var body: some View {
+        Group {
+            switch appState.phase {
+            case .checking:
+                LaunchView()
+            case .signedOut:
+                // Provided by Features/Auth/AuthFlowView.swift
+                AuthFlowView()
+            case .signedIn:
+                // Provided by Features/Root/MainTabView.swift
+                MainTabView()
+            }
+        }
+        .animation(.default, value: appState.phase)
+    }
+}
+
+private struct LaunchView: View {
+    var body: some View {
+        VStack(spacing: ZenithSpacing.xs) {
+            Image(systemName: "doc.text.viewfinder")
+                .font(.system(size: 44))
+                .foregroundStyle(.zenithBlack)
+            ProgressView()
+                .tint(.zenithBlack)
+        }
+        .frame(maxWidth: .infinity, maxHeight: .infinity)
+        .background(Color.zenithBg)
+    }
+}