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.

package-lock.json

@@ -455,8 +455,8 @@
       }
     },
     "node_modules/@einfach-produktiv/invoicing": {
-      "version": "0.2.7",
-      "resolved": "git+https://git.mk360.de/Marco/einfach-produktiv-invoicing.git#e66007cc4aacccf3b1f18892f3ae9a5e6adf685e",
+      "version": "0.2.8",
+      "resolved": "git+https://git.mk360.de/Marco/einfach-produktiv-invoicing.git#ed96d36b54ba529a9ce4bf4a8ee94fd4c2a50d90",
       "dependencies": {
         "@e-invoice-eu/core": "^3.1.1"
       },