Add Relay returns and QR checkout demo

dist/returns.mjs

@@ -0,0 +1,30 @@
+import {run} from "./engine.mjs";
+
+const reasons = new Set(["damaged","wrong-item","changed-mind","other"]);
+export function submitReturn({order,reason}, storage) {
+  const id = String(order ?? "").trim().toUpperCase();
+  if (!/^RX-\d{3}$/.test(id)) return {status:"invalid",message:"Enter an order number in the format RX-104."};
+  if (!reasons.has(reason)) return {status:"invalid",message:"Choose a reason for the return."};
+  const decision = run(id);
+  if (decision.status !== "review") {
+    return {
+      status: decision.status,
+      message: decision.status === "retry"
+        ? "We couldn’t reach the order service. No refund was processed. Please try again later."
+        : decision.status === "clarify"
+        ? "We couldn’t find that order. Check your order number and try again."
+        : decision.reply
+    };
+  }
+  const key = "relay.demo.refund." + id;
+  try {
+    const raw = storage.getItem(key);
+    const existing = raw ? JSON.parse(raw) : null;
+    if (existing) return {status:"duplicate",receipt:existing,message:"A demo refund already exists for this order. No second refund was processed."};
+    const receipt = {id:"RF-" + id.slice(3),order:id,amount:decision.draft.amount,reason};
+    storage.setItem(key,JSON.stringify(receipt));
+    return {status:"refunded",receipt,message:"Your return was approved and the demo refund was processed automatically."};
+  } catch {
+    return {status:"retry",message:"We couldn’t save your return in this browser. No refund was confirmed. Enable site storage and try again."};
+  }
+}