Update payment method

## Update invoice payment method Changes the payment method selected for the still-open invoice `:id` — e.g. switching between Lightning wallets or to cash — and recomputes the payment destination and crypto amount for the new method. This replaces the deprecated `PATCH /v1/invoice/pm`, which took the invoice id in the body. ### Auth `x-api-key` header with **`Merchant.invoice.patch`**. Also accepts JWT user and POS JWT. ### Path params - `id` (required): the invoice id. ### Body (application/json) - `paymentMethodId` — the target payment method (a `PaymentMethodsLike` value, e.g. `BTC_StrikeLike`, `CASH`). ### Errors - **400** `Cannot update payment method on a closed or expired invoice.` — the invoice is not in `New` status. - **400** `The selected payment method is not available for this store.` — the method is not enabled for the store (this is also what you get if you omit `paymentMethodId`). - **400** `Payment method data not found in the invoice.` — the invoice carries no crypto data for that method. --- **Notas:** Handler: updatepmService.updateInvoicePaymentType({ invoiceId: <path id>, paymentMethodId }). `paymentMethodId` is declared @IsOptional in UpdatePMBodyDto, so validation lets it through, but omitting it always ends in a 400 — treat it as required. Emits a PAYMENT_METHOD_UPDATED invoice event.