fix(mobile): configure Purchases on menu editor load

"There is no singleton instance" when tapping Yayınla — the app can
land directly on /menu (e.g. iOS restoring the last screen on
relaunch) without ever running index.tsx's routing gate, so
Purchases.configure() was never called. Menu editor's load() now
configures it defensively too, same pattern as account/subscription.tsx.

apps/mobile/src/app/menu/index.tsx

@@ -16,7 +16,7 @@ import * as Haptics from "expo-haptics";
 import { api } from "@/lib/api";
 import { getActiveRestaurant, type ActiveRestaurant } from "@/lib/active-restaurant";
 import { getPublicMenuUrl, getPublicMenuDisplayUrl } from "@/lib/urls";
-import { getCustomerInfo, isProActive } from "@/lib/purchases";
+import { configurePurchases, getCustomerInfo, isProActive } from "@/lib/purchases";
 import { CategoryPillBar } from "@/components/menu/CategoryPillBar";
 import { MenuItemCard, type MenuItemData } from "@/components/menu/MenuItemCard";
 import { ItemDetailSheet } from "@/components/menu/ItemDetailSheet";
@@ -67,6 +67,7 @@ export default function MenuEditorScreen() {
         return;
       }
       setActive(cached);
+      configurePurchases(cached.restaurantId);
 
       const data = await api.get<MenuResponse>(`/menus/${cached.menuId}`);
       setMenu(data.menu);