Send a dedicated email for a switched Überweisung payment, not the full order-confirmation

New sendPaymentSwitchedEmail() — sent instead of sendOrderConfirmationEmail()
when confirmPaymentEmail.ts sees order.paymentSwitchedAt set. Resending the
full order-confirmation (with its invoice re-attached) after a payment-method
switch read like a brand-new purchase; this is a short, dedicated "Zahlung
erhalten" confirmation instead, matching the order-status-email shape.

Also bumps @einfach-produktiv/invoicing to 0.2.8, fixing a font-path bug
that broke every invoice PDF render inside the Payload backend specifically.

app/lib/emailTemplates.ts

@@ -335,6 +335,7 @@ export const ORDER_STATUS_EMAIL_ICON: Record<string, string> = {
   "order-tracking-added": "📦",
   "order-tracking-corrected": "📦",
   "order-delivered": "🎉",
+  "payment-method-switched": "💳",
 };
 
 export function renderOrderStatusHtml(