feat: add iOS support and harden receipt scanning

app/ios/ScanReceipts/Design/ZenithCard.swift

@@ -0,0 +1,35 @@
+import SwiftUI
+
+/// Cards per `DESIGN (1).md` → Components → Cards: "White backgrounds with
+/// 1px borders in #E2E8F0. No shadows. Content within cards should follow
+/// the 24px internal padding rule." And → Shapes: 0px radius everywhere.
+struct ZenithCardModifier: ViewModifier {
+    var padding: CGFloat = ZenithSpacing.cardPadding
+
+    func body(content: Content) -> some View {
+        content
+            .padding(padding)
+            .background(Color.zenithSurface)
+            .overlay(Rectangle().strokeBorder(Color.zenithBorder, lineWidth: 1))
+        // Deliberately no `.cornerRadius` and no `.shadow` — both are
+        // explicitly rejected by the design system ("rejects traditional
+        // shadows and depth", "0px radius" everywhere).
+    }
+}
+
+extension View {
+    func zenithCard(padding: CGFloat = ZenithSpacing.cardPadding) -> some View {
+        modifier(ZenithCardModifier(padding: padding))
+    }
+
+    /// Strips the default iOS `List`/`Form` chrome (rounded row groups,
+    /// system grey background, inset grouping) toward the flat,
+    /// bordered-card look the rest of this design system uses. Apply to a
+    /// `List`/`Form`; still combine with `.listRowBackground(Color.zenithSurface)`
+    /// and `.listRowSeparatorTint(Color.zenithBorder)` on individual rows if
+    /// you want row separators to match instead of disappearing.
+    func zenithListBackground() -> some View {
+        scrollContentBackground(.hidden)
+            .background(Color.zenithBg)
+    }
+}