refactor(automations): detect manual payment via OrderTransaction.manualPaymentGateway

- Drop wireTransferGatewayNames from ShopSettings (new migration).
- Replace string-matching with a GraphQL query against
  Order.transactions[].manualPaymentGateway, the first-class flag
  Shopify exposes for any merchant-defined manual payment method.
- Both webhook handlers now fetch the order on the fly to classify it,
  removing the configurable gateway-names field from settings.

prisma/schema.prisma

@@ -105,10 +105,6 @@ model ShopSettings {
   autoEmailOnWireTransferPlaced     Boolean @default(false)
   // 2) Order is fulfilled and is NOT a wire-transfer order → auto-email.
   autoEmailOnFulfilledNonWireTransfer Boolean @default(false)
-  // Comma-separated list of payment-gateway names treated as "wire transfer"
-  // (matched case-insensitively, substring). Empty falls back to a sensible
-  // default ("manual,Überweisung,Wire Transfer,Bank Transfer,Vorkasse,Bank Deposit").
-  wireTransferGatewayNames          String  @default("")
 
   createdAt         DateTime @default(now())
   updatedAt         DateTime @updatedAt