fix(pos): show the post-payment receipt sheet (was rendered in the wrong view)

The payment-success sheet with the "چاپ فاکتور" button lives in the order-view
return, but confirmPay called backToBoard() which switched to the board view —
so the sheet never rendered and the cashier couldn't print after paying.

Now payment clears the cart + closes the pay sheet but STAYS on the order view,
so the success sheet shows; returning to the board happens when the cashier taps
"سفارش جدید" or the backdrop. Offline/local orders still go straight to the board.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/dashboard/src/components/pos2/pos2-screen.tsx

@@ -293,10 +293,14 @@ export function Pos2Screen() {
       notify.success(`پرداخت ${fmt(paid)} تومان ثبت شد`);
       queryClient.invalidateQueries({ queryKey: ["tables-board", cafeId] });
       queryClient.invalidateQueries({ queryKey: ["orders-open", cafeId] });
-      backToBoard();
-      // Keep the paid order id so the cashier can still print the receipt after
-      // the cart is cleared (the success sheet below uses it).
+      // Clear the cart + close the pay sheet, but STAY on the order view so the
+      // payment-success sheet (which lives in this view) renders and the cashier
+      // can print the receipt. Going back to the board happens on dismiss.
+      clearSession();
+      setPayTarget(null);
+      setCartOpen(false);
       if (!isLocalOrder(justPaidOrderId)) setPaidOrderId(justPaidOrderId);
+      else backToBoard();
     } catch (e) {
       if (e instanceof ApiClientError && e.code.startsWith("POS_DEVICE")) {
         notify.error(posDeviceMsg(e));
@@ -616,7 +620,7 @@ export function Pos2Screen() {
 
       {paidOrderId && (
         <div dir="rtl" className="fixed inset-0 z-[65] flex items-center justify-center p-4">
-          <div className="absolute inset-0 bg-black/50" onClick={() => setPaidOrderId(null)} />
+          <div className="absolute inset-0 bg-black/50" onClick={() => { setPaidOrderId(null); backToBoard(); }} />
           <div className="relative w-full max-w-sm rounded-2xl bg-card p-6 text-center shadow-2xl">
             <div className="mx-auto mb-3 flex size-14 items-center justify-center rounded-full bg-emerald-100 text-emerald-600">
               <Check className="size-7" />
@@ -633,7 +637,7 @@ export function Pos2Screen() {
               </button>
               <button
                 type="button"
-                onClick={() => setPaidOrderId(null)}
+                onClick={() => { setPaidOrderId(null); backToBoard(); }}
                 className="flex min-h-[48px] w-full items-center justify-center rounded-xl bg-muted text-sm font-medium text-foreground hover:bg-accent"
               >
                 سفارش جدید