feat: add better tab view

apps/api/templates/emails/README.md

@@ -60,3 +60,21 @@ Sent by the test button next to a customer's email address.
 |---|---|
 | `{{customerName}}` | Jan Peeters |
 | `{{venueName}}` | Café De Kroon |
+
+### `cash-payment`
+
+Sent to the venue's cash payment addresses (dashboard settings) whenever a tab is paid in cash, on a terminal or on
+the dashboard.
+
+| Placeholder | Example |
+|---|---|
+| `{{customerName}}` | Jan Peeters |
+| `{{venueName}}` | Café De Kroon |
+| `{{amount}}` | € 29,00 |
+| `{{settledAt}}` | 27 oktober 2026 om 22:15 |
+| `{{settledBy}}` | Bar tablet, or the dashboard user's name |
+| `{{#hasItems}}…{{/hasItems}}` | Shown when anything was paid for |
+| `{{#items}}…{{/items}}` | Repeated for each paid line, with: |
+|   `{{quantity}}` | 10 |
+|   `{{productName}}` | Cola |
+|   `{{lineTotal}}` | € 25,00 |