feat(orders): implement QA audit fixes — return flow, refund webhook, TS cleanup

Convex backend (AUDIT-5–10):
- schema: add returnLabelUrl, returnTrackingNumber, returnCarrier fields +
  by_return_tracking_number_and_carrier and by_stripe_payment_intent_id indexes
- orders: markReturnReceived now sets status="completed"; add getOrderByPaymentIntent
  and applyReturnAccepted internal helpers
- returnActions: add acceptReturn action — creates Shippo return label (is_return:true),
  persists label data, sends return label email to customer
- stripeActions: handle refund.updated webhook to auto-mark orders refunded via Stripe Dashboard
- shippoWebhook: add getOrderByReturnTracking; applyTrackingUpdate extended with
  isReturnTracking flag (return events use return_tracking_update type, skip delivered transition)
- emails: add sendReturnLabelEmail; fulfillmentActions: createShippingLabel action

Admin UI (AUDIT-1–6):
- OrderActionsBar: full rewrite per authoritative action matrix; remove UpdateStatusDialog;
  add AcceptReturnButton for delivered+returnRequested state
- AcceptReturnButton: new action component matching CreateLabelButton pattern
- FulfilmentCard: add returnLabelUrl prop; show "Return label" row; rename outbound
  label to "Outbound label" when both are present
- statusConfig: add return_accepted to OrderEventType and EVENT_TYPE_LABELS
- orders detail page and all supporting cards/components

Storefront & shared (TS fixes):
- checkout/success, CheckoutErrorState, OrderReviewStep, PaymentStep: replace
  Button as/color/isLoading/variant="flat" with HeroUI v3-compatible props
- ReviewList: isLoading → isPending for HeroUI v3 Button
- packages/utils: add return and completed entries to ORDER_STATUS_LABELS/COLORS

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/utils/src/index.ts

@@ -122,6 +122,8 @@ export const ORDER_STATUS_LABELS: Record<OrderStatus, string> = {
   delivered: "Delivered",
   cancelled: "Cancelled",
   refunded: "Refunded",
+  return: "Return Requested",
+  completed: "Completed",
 };
 
 export const PAYMENT_STATUS_LABELS: Record<PaymentStatus, string> = {
@@ -139,6 +141,8 @@ export const ORDER_STATUS_COLORS: Record<OrderStatus, string> = {
   delivered: "green",
   cancelled: "red",
   refunded: "gray",
+  return: "orange",
+  completed: "teal",
 };
 
 // ─── Validation ───────────────────────────────────────────────────────────────