Treat 404 in incoming-order actions as "no longer available"

Task #87: Confirm-receipt should also handle the case where the order was
deleted.

When an admin deletes an order while a receiver is viewing it, the API
returns 404 Order not found for confirm-receipt and the status PATCH.
Previously the UI showed the generic "Could not complete the action"
toast and left the stale card in place.

Updated all three onError branches in
`artifacts/tx-os/src/pages/orders-incoming.tsx` so 404 responses are
handled the same way as the existing `order_unavailable` 409:

- handleConfirmReceipt: 404 now shows the localized
  "incomingOrders.orderUnavailable" toast instead of "actionFailed".
  invalidate() was already called for every error in this branch, so
  the stale card is removed.
- handleSetStatus (preparing/completed): 404 now shows the
  "orderUnavailable" toast and calls invalidate() to drop the card.
- handleCancel: same treatment for 404 on the cancel PATCH.

The 409 already-claimed branch is preserved unchanged. No new
translation keys were needed; `incomingOrders.orderUnavailable` already
exists in both `src/locales/en.json` and `src/locales/ar.json`.

Pre-existing TypeScript errors in `src/pages/admin.tsx` are unrelated
to this change.

Replit-Task-Id: a923d4f2-0a45-4816-aee9-0822c5677b88

artifacts/tx-os/src/pages/orders-incoming.tsx

@@ -122,7 +122,10 @@ function IncomingOrderCard({
           const apiErr = err as { status?: number; data?: { error?: string } } | null;
           const status = apiErr?.status;
           const code = apiErr?.data?.error;
-          if (status === 409 && code === "order_unavailable") {
+          if (
+            (status === 409 && code === "order_unavailable") ||
+            status === 404
+          ) {
             toast({
               title: t("incomingOrders.orderUnavailable"),
               variant: "destructive",
@@ -158,7 +161,10 @@ function IncomingOrderCard({
         },
         onError: (err: unknown) => {
           const apiErr = err as { status?: number; data?: { error?: string } } | null;
-          if (apiErr?.status === 409 && apiErr?.data?.error === "order_unavailable") {
+          if (
+            (apiErr?.status === 409 && apiErr?.data?.error === "order_unavailable") ||
+            apiErr?.status === 404
+          ) {
             toast({
               title: t("incomingOrders.orderUnavailable"),
               variant: "destructive",
@@ -220,7 +226,10 @@ function IncomingOrderCard({
         },
         onError: (err: unknown) => {
           const apiErr = err as { status?: number; data?: { error?: string } } | null;
-          if (apiErr?.status === 409 && apiErr?.data?.error === "order_unavailable") {
+          if (
+            (apiErr?.status === 409 && apiErr?.data?.error === "order_unavailable") ||
+            apiErr?.status === 404
+          ) {
             toast({
               title: t("incomingOrders.orderUnavailable"),
               variant: "destructive",