feat(payment): implement change payment method (PATCH /payment-method)

- ChangePaymentMethodPayload + ChangePaymentMethodResult models
- ApiService.changePaymentMethod()
- PixPaymentContext gains storeId + order data for payment switch
- PaymentPixView: Trocar button opens ChangePaymentSheet with 3 options
- ChangePaymentSheet: Novo PIX (new QR), Cartão (saved or new), Pagar na Entrega
- ChangePaymentCardSheet + ChangePaymentNewCardView with same card masks/validation
- OrdersView/OrderEntryDestinationView: threaded appState binding

pedi-foods/Sources/PediFoods/Services/ApiCardModels.swift

@@ -65,3 +65,19 @@ struct CreditCardOrderPayload: Encodable {
     let expiryYear: String
     let ccv: String
 }
+
+struct ChangePaymentMethodPayload: Encodable {
+    let paymentMethod: String
+    let clientCpfCnpj: String?
+    let creditCard: CreditCardOrderPayload?
+    let creditCardHolderInfo: SaveCardHolderInfoPayload?
+    let savedCardId: String?
+}
+
+struct ChangePaymentMethodResult: Decodable {
+    let paymentMethod: String?
+    let paymentLocation: String?
+    let paymentId: String?
+    let paymentPayload: CreateOrderPaymentPayload?
+    let payment: CreateOrderPaymentInfo?
+}