feat(bills): capture event name/date when importing historical invoices

The historical-invoice import form had no event field, so imported rows
landed with event_name = NULL even when the admin knew the occasion. Add
free-text Event name + Event date inputs to the import modal, thread them
through billsService.importHistorical and the POST /admin/invoices/import
validator, and store them in the event_name/event_date snapshot columns
(migration 107). event_id stays NULL — no FK, since the event may predate
picpeak. Autocomplete-to-event_id linking deferred as a future bonus.

backend/src/routes/adminInvoices.js

@@ -427,6 +427,8 @@ router.post(
   [
     body('customerAccountId').isInt({ min: 1 }),
     body('invoiceNumber').isString().isLength({ min: 1, max: 64 }),
+    body('eventName').optional({ values: 'falsy' }).isString().isLength({ max: 255 }),
+    body('eventDate').optional({ values: 'falsy' }).isISO8601(),
     body('issueDate').isISO8601(),
     body('dueDate').optional({ values: 'falsy' }).isISO8601(),
     body('totalAmountMinor').isInt({ min: 0 }),
@@ -487,7 +489,12 @@ router.post(
       invoice_number: req.body.invoiceNumber,
       customer_account_id: customer.id,
       source_quote_id: null,
+      // No FK link on import — the event may predate picpeak. Store the
+      // free-text snapshot only, mirroring createInvoice's event_name /
+      // event_date columns (migration 107).
       event_id: null,
+      event_name: req.body.eventName || null,
+      event_date: req.body.eventDate || null,
       language,
       currency,
       issue_date: issueDate,

frontend/src/i18n/locales/de.json

@@ -3541,6 +3541,7 @@
       "selectTiming": "— Zahlungsablauf wählen —",
       "eventName": "Anlass",
       "eventDate": "Anlassdatum",
+      "eventNamePlaceholder": "z.B. Hochzeit Schmidt 2024",
       "eventTimeStart": "Startzeit",
       "eventTimeEnd": "Endzeit",
       "customer": "Kunde",

frontend/src/i18n/locales/en.json

@@ -3587,6 +3587,7 @@
       "selectTiming": "— Select schedule —",
       "eventName": "Event",
       "eventDate": "Event date",
+      "eventNamePlaceholder": "e.g. Smith wedding 2024",
       "eventTimeStart": "Start time",
       "eventTimeEnd": "End time",
       "customer": "Customer",

frontend/src/pages/admin/bills/BillsListPage.tsx

@@ -221,6 +221,8 @@ const ImportHistoricalInvoiceModal: React.FC<ImportModalProps> = ({ onClose }) =
   const [customerId, setCustomerId] = useState<number | null>(null);
   const [customerLabel, setCustomerLabel] = useState('');
   const [invoiceNumber, setInvoiceNumber] = useState('');
+  const [eventName, setEventName] = useState('');
+  const [eventDate, setEventDate] = useState('');
   const [issueDate, setIssueDate] = useState(new Date().toISOString().slice(0, 10));
   const [dueDate, setDueDate] = useState('');
   const [totalMajor, setTotalMajor] = useState('');
@@ -245,6 +247,8 @@ const ImportHistoricalInvoiceModal: React.FC<ImportModalProps> = ({ onClose }) =
       await billsService.importHistorical({
         customerAccountId: customerId,
         invoiceNumber,
+        eventName: eventName.trim() || undefined,
+        eventDate: eventDate || undefined,
         issueDate,
         dueDate: dueDate || undefined,
         totalAmountMinor: Math.round(Number(totalMajor) * 100),
@@ -327,6 +331,17 @@ const ImportHistoricalInvoiceModal: React.FC<ImportModalProps> = ({ onClose }) =
           </div>
 
           <div className="grid grid-cols-1 md:grid-cols-2 gap-3">
+            <div className="md:col-span-2">
+              <Input label={t('bills.field.eventName', 'Event / occasion (optional)') as string}
+                value={eventName}
+                placeholder={t('bills.field.eventNamePlaceholder', 'e.g. Smith wedding 2024') as string}
+                onChange={(e) => setEventName(e.target.value)} />
+            </div>
+            <LocalizedDateInput
+              label={t('bills.field.eventDate', 'Event date (optional)') as string}
+              value={eventDate}
+              onChange={setEventDate}
+            />
             <Input label={t('bills.field.invoiceNumber', 'Invoice number') as string}
               value={invoiceNumber}
               placeholder="R-2024-0001"

frontend/src/services/bills.service.ts

@@ -330,6 +330,8 @@ export const billsService = {
   async importHistorical(payload: {
     customerAccountId: number;
     invoiceNumber: string;
+    eventName?: string;
+    eventDate?: string;
     issueDate: string;
     dueDate?: string;
     totalAmountMinor: number;
@@ -343,6 +345,8 @@ export const billsService = {
     form.append('pdf', payload.file);
     form.append('customerAccountId', String(payload.customerAccountId));
     form.append('invoiceNumber', payload.invoiceNumber);
+    if (payload.eventName) form.append('eventName', payload.eventName);
+    if (payload.eventDate) form.append('eventDate', payload.eventDate);
     form.append('issueDate', payload.issueDate);
     if (payload.dueDate) form.append('dueDate', payload.dueDate);
     form.append('totalAmountMinor', String(payload.totalAmountMinor));