feat: add iOS support and harden receipt scanning

app/ios/ScanReceipts/Support/ISO8601.swift

@@ -0,0 +1,25 @@
+import Foundation
+
+/// The backend serialises every timestamp with `Date.prototype.toISOString()`,
+/// which always includes milliseconds (`...307Z`). `ISO8601DateFormatter`'s
+/// default options reject that string, so every date in this app must go
+/// through this helper rather than a bare `ISO8601DateFormatter()` — using
+/// the wrong one is a silent-failure trap, not a compile error.
+enum ISO8601 {
+    private static let withFractional: ISO8601DateFormatter = {
+        let f = ISO8601DateFormatter()
+        f.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+        return f
+    }()
+
+    private static let withoutFractional: ISO8601DateFormatter = {
+        let f = ISO8601DateFormatter()
+        f.formatOptions = [.withInternetDateTime]
+        return f
+    }()
+
+    static func parse(_ string: String?) -> Date? {
+        guard let string else { return nil }
+        return withFractional.date(from: string) ?? withoutFractional.date(from: string)
+    }
+}