feat(orders): per-item kitchen/bar notes (POS + QR app + KDS)

Lets the POS agent and the QR/app customer attach a free-text note to each
order line (e.g. "no tomato", "extra hot") that reaches the kitchen/bar.

- Backend already supported it (OrderItem.Notes persists; CreateOrderItemRequest
  and OrderItemDto carry Notes; LiveOrderDto items include it) — this wires the UI.
- cart.store: add setNotes(menuItemId, notes); notes already travel in
  getPendingLines and round-trip via hydrateFromOrder.
- POS pos-screen: a note input under each cart line.
- QR guest menu: a note input under each cart line (QrCartLine.note).
- KDS: render the note prominently under each item so kitchen/bar sees it.
- i18n: pos.itemNotePlaceholder + qrMenu.itemNote (fa/ar/en).

Note: notes are captured on items being added; editing a note on an
already-submitted line is out of scope (no pending delta to re-send).

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

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

@@ -255,6 +255,7 @@ export function PosScreen() {
     addItem,
     removeItem,
     updateQty,
+    setNotes,
     couponCode,
     appliedCoupon,
     setCouponCode,
@@ -1210,10 +1211,11 @@ export function PosScreen() {
                       <div
                         key={line.orderItemId ?? line.menuItem.id}
                         className={cn(
-                          "flex items-center gap-2 rounded-lg border border-border p-2",
+                          "flex flex-col gap-1.5 rounded-lg border border-border p-2",
                           line.isVoided && "opacity-60"
                         )}
                       >
+                        <div className="flex items-center gap-2">
                         <div className="min-w-0 flex-1">
                           <MenuItemLabels
                             item={line.menuItem}
@@ -1291,6 +1293,18 @@ export function PosScreen() {
                             </>
                           ) : null}
                         </div>
+                        </div>
+                        {!line.isVoided && (
+                          <input
+                            type="text"
+                            value={line.notes ?? ""}
+                            onChange={(e) => setNotes(line.menuItem.id, e.target.value)}
+                            onClick={(e) => e.stopPropagation()}
+                            onKeyDown={(e) => e.stopPropagation()}
+                            placeholder={t("itemNotePlaceholder")}
+                            className="w-full rounded-md border border-border/70 bg-background px-2 py-1 text-[11px] placeholder:text-muted-foreground focus:outline-none focus:ring-1 focus:ring-primary/40"
+                          />
+                        )}
                       </div>
                     ))
                   )}