feat(accounting): event booking via dropdown (Company or an event)

Replaces the Company/Event toggle + numeric Event-ID input with a single
EventBookingSelect dropdown (Company = null, else a specific event, fetched via
eventsService). Used by both the incoming-invoice triage and the expense add
form. Projects stay a separate aggregation of events and are intentionally not
a booking target here.

Verified: tsc --noEmit clean; npm run build green.

frontend/src/components/admin/EventBookingSelect.tsx

@@ -0,0 +1,39 @@
+/**
+ * Booking-target dropdown for accounting (expenses + incoming invoices).
+ * "Company" (value null) or a specific event. Projects remain a separate
+ * aggregation of events and are intentionally NOT a booking target here.
+ */
+import React from 'react';
+import { useQuery } from '@tanstack/react-query';
+import { useTranslation } from 'react-i18next';
+import { eventsService } from '../../services/events.service';
+
+interface Props {
+  value: number | null;
+  onChange: (eventId: number | null) => void;
+  className?: string;
+}
+
+export const EventBookingSelect: React.FC<Props> = ({ value, onChange, className }) => {
+  const { t } = useTranslation();
+  const { data } = useQuery({
+    queryKey: ['events-for-booking'],
+    queryFn: () => eventsService.getEvents(1, 200),
+    staleTime: 60_000,
+  });
+  const events = data?.events ?? [];
+  const cls = className
+    || 'w-full rounded-md border border-neutral-300 dark:border-neutral-600 bg-white dark:bg-neutral-800 px-3 py-2 text-sm';
+
+  return (
+    <select className={cls} value={value == null ? '' : String(value)}
+      onChange={(e) => onChange(e.target.value ? Number(e.target.value) : null)}>
+      <option value="">{t('accounting.booking.company', 'Company')}</option>
+      {events.map((ev) => (
+        <option key={ev.id} value={ev.id}>{ev.event_name}</option>
+      ))}
+    </select>
+  );
+};
+
+export default EventBookingSelect;

frontend/src/pages/admin/accounting/AccountingInboxPage.tsx

@@ -13,6 +13,7 @@ import { Camera, Upload, Inbox, X, CheckCircle2, Circle } from 'lucide-react';
 import { Button, Card, CardContent, Input, LocalizedDateInput, Loading } from '../../../components/common';
 import { DecimalInput } from '../../../components/common/DecimalInput';
 import { CustomerAccountPicker, type SelectedCustomer } from '../../../components/admin/CustomerAccountPicker';
+import { EventBookingSelect } from '../../../components/admin/EventBookingSelect';
 import { formatMoneyMinor } from '../../../utils/money';
 import { useLocalizedDate } from '../../../hooks/useLocalizedDate';
 import {
@@ -34,27 +35,6 @@ const statusClasses: Record<string, string> = {
 const labelCls = 'block text-sm font-medium text-neutral-700 dark:text-neutral-300 mb-1';
 const selectCls = 'w-full rounded-md border border-neutral-300 dark:border-neutral-600 bg-white dark:bg-neutral-800 px-3 py-2 text-sm';
 
-const BookingField: React.FC<{ eventId: number | null; onChange: (id: number | null) => void }> = ({ eventId, onChange }) => {
-  const { t } = useTranslation();
-  const isEvent = eventId != null;
-  return (
-    <div>
-      <label className={labelCls}>{t('accounting.booking.label', 'Book to')}</label>
-      <div className="flex gap-2">
-        <select className={selectCls} style={{ maxWidth: 160 }} value={isEvent ? 'event' : 'company'}
-          onChange={(e) => onChange(e.target.value === 'event' ? (eventId ?? 0) : null)}>
-          <option value="company">{t('accounting.booking.company', 'Company')}</option>
-          <option value="event">{t('accounting.booking.event', 'Event')}</option>
-        </select>
-        {isEvent && (
-          <Input placeholder={t('accounting.booking.eventId', 'Event ID')} inputMode="numeric"
-            value={eventId ? String(eventId) : ''} onChange={(e) => onChange(Number(e.target.value.replace(/[^0-9]/g, '')) || 0)} />
-        )}
-      </div>
-    </div>
-  );
-};
-
 const PayModal: React.FC<{ doc: InboundDocument; onClose: () => void; onDone: () => void }> = ({ doc, onClose, onDone }) => {
   const { t } = useTranslation();
   const [paidAt, setPaidAt] = useState('');
@@ -184,7 +164,12 @@ const TriageModal: React.FC<{ doc: InboundDocument; categories: ExpenseCategory[
               </select>
             </div>
 
-            {BOOKING_DISPOSITIONS.includes(disposition) && <BookingField eventId={eventId} onChange={setEventId} />}
+            {BOOKING_DISPOSITIONS.includes(disposition) && (
+              <div>
+                <label className={labelCls}>{t('accounting.booking.label', 'Book to')}</label>
+                <EventBookingSelect value={eventId} onChange={setEventId} className={selectCls} />
+              </div>
+            )}
 
             {disposition === 'eigener_aufwand' && (
               <div><label className={labelCls}>{t('accounting.inbox.field.category', 'Category')}</label>

frontend/src/pages/admin/accounting/ExpensesLedgerPage.tsx

@@ -13,6 +13,7 @@ import { toast } from 'react-toastify';
 import { X, Plus, Paperclip, Car, CalendarDays, Coins } from 'lucide-react';
 import { Button, Card, CardContent, Input, Loading } from '../../../components/common';
 import { DecimalInput } from '../../../components/common/DecimalInput';
+import { EventBookingSelect } from '../../../components/admin/EventBookingSelect';
 import { formatMoneyMinor } from '../../../utils/money';
 import { useLocalizedDate } from '../../../hooks/useLocalizedDate';
 import {
@@ -106,13 +107,7 @@ const AddExpenseModal: React.FC<{ categories: ExpenseCategory[]; onClose: () =>
           </div>
 
           <div><label className={labelCls}>{t('accounting.booking.label', 'Book to')}</label>
-            <div className="flex gap-2">
-              <select className={selectCls} style={{ maxWidth: 160 }} value={eventId != null ? 'event' : 'company'} onChange={(e) => setEventId(e.target.value === 'event' ? (eventId ?? 0) : null)}>
-                <option value="company">{t('accounting.booking.company', 'Company')}</option>
-                <option value="event">{t('accounting.booking.event', 'Event')}</option>
-              </select>
-              {eventId != null && <Input placeholder={t('accounting.booking.eventId', 'Event ID')} inputMode="numeric" value={eventId ? String(eventId) : ''} onChange={(e) => setEventId(Number(e.target.value.replace(/[^0-9]/g, '')) || 0)} />}
-            </div>
+            <EventBookingSelect value={eventId} onChange={setEventId} className={selectCls} />
           </div>
 
           <div>