Add per-event finance, event team permissions and public door sales state.

Event finance
- Finance tab on the event page: P&L summary with a revenue-to-result
  waterfall, costs and other income in one ledger, and the partner split
  with payouts. Lifecycle stepper (Selling, Adding costs, Ready to close,
  Finalized) with what is left to do; closing the books goes through a
  checklist dialog that freezes the numbers.
- Expense modal shows only the fields each calculation type needs, a live
  preview with the event's real counts, and a category suggested from the
  description. Date inputs follow the UI language.
- Global Finance page: profit per event with outliers clipped and labelled,
  and a "Ready to close" list of past events whose books are still open.
- Calculation service (integer PYG, basis points) with pinned regression
  scenarios; PYG formatting centralised in lib/money with locale-aware
  separators.

Event team permissions
- Per-event members with role presets and requireEventPermission; the
  header stat "Confirmed" is relabelled "Not checked in yet", which is
  what it counts.

Public sales state
- One sales state (online, door, sold out, ended, external, cancelled) for
  the event page, listings and JSON-LD, with the door price and tenders
  shown only while people can still pay at the door.

Frontend unit tests run with vitest (npm test in frontend/).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/app/admin/events/[id]/_finance/FinanceTab.tsx

@@ -0,0 +1,91 @@
+'use client';
+
+import { useCallback, useEffect, useMemo, useState } from 'react';
+import toast from 'react-hot-toast';
+import { useLanguage } from '@/context/LanguageContext';
+import { financeApi, type EventFinance } from '@/lib/api';
+import { Skeleton } from '@/components/ui/Skeleton';
+import { SubNav } from './ui';
+import { SummaryView } from './SummaryView';
+import { ExpensesView } from './ExpensesView';
+import { SplitView } from './SplitView';
+import { LifecycleStepper } from './LifecycleStepper';
+import { deriveLifecycle } from './derive';
+
+export type FinanceSection = 'summary' | 'expenses' | 'split';
+const SECTIONS: FinanceSection[] = ['summary', 'expenses', 'split'];
+
+/** Keep the open section in the URL (?fin=expenses) so reloads and shared links land on it. */
+function readSection(): FinanceSection {
+  if (typeof window === 'undefined') return 'summary';
+  const v = new URLSearchParams(window.location.search).get('fin');
+  return SECTIONS.includes(v as FinanceSection) ? (v as FinanceSection) : 'summary';
+}
+function writeSection(section: FinanceSection) {
+  const url = new URL(window.location.href);
+  if (section === 'summary') url.searchParams.delete('fin'); else url.searchParams.set('fin', section);
+  window.history.replaceState(window.history.state, '', url);
+}
+
+/**
+ * Finance tab: P&L summary with charts, expenses and other income, and the
+ * partner split with payouts. The server already scopes what comes back (e.g.
+ * collaborators only get their own share), so this renders what it receives.
+ */
+export function FinanceTab({ eventId }: { eventId: string }) {
+  const { t } = useLanguage();
+  const [data, setData] = useState<EventFinance | null>(null);
+  const [loading, setLoading] = useState(true);
+  const [section, setSectionState] = useState<FinanceSection>('summary');
+
+  useEffect(() => { setSectionState(readSection()); }, []);
+  const setSection = useCallback((s: FinanceSection) => { setSectionState(s); writeSection(s); }, []);
+
+  const load = useCallback(async () => {
+    try {
+      setData(await financeApi.get(eventId));
+    } catch (error: any) {
+      toast.error(error.message || t('admin.finance.loadError'));
+    } finally {
+      setLoading(false);
+    }
+  }, [eventId, t]);
+
+  useEffect(() => { load(); }, [load]);
+  // Recomputed with every reload, so "ended X days ago" stays current.
+  const lifecycle = useMemo(() => (data ? deriveLifecycle(data) : null), [data]);
+
+  if (loading) {
+    return (
+      <div className="space-y-3" aria-busy="true">
+        <Skeleton className="h-24" />
+        <Skeleton className="h-11 w-full md:w-96" />
+        <div className="grid grid-cols-2 lg:grid-cols-4 gap-3">
+          {Array.from({ length: 4 }).map((_, i) => <Skeleton key={i} className="h-24" />)}
+        </div>
+        <Skeleton className="h-64" />
+      </div>
+    );
+  }
+  if (!data || !lifecycle) return <p className="text-sm text-gray-500 py-8 text-center">{t('admin.finance.loadError')}</p>;
+
+  return (
+    <div className="space-y-4">
+      <LifecycleStepper data={data} lifecycle={lifecycle} goTo={setSection} />
+
+      <SubNav<FinanceSection>
+        items={[
+          { key: 'summary', label: t('admin.finance.subnav.summary') },
+          { key: 'expenses', label: t('admin.finance.subnav.expenses'), count: data.expenses.length + data.otherIncome.length },
+          { key: 'split', label: t('admin.finance.subnav.split'), count: data.partners.length },
+        ]}
+        active={section}
+        onChange={setSection}
+      />
+
+      {section === 'summary' && <SummaryView data={data} goTo={setSection} />}
+      {section === 'expenses' && <ExpensesView eventId={eventId} data={data} onChange={load} />}
+      {section === 'split' && <SplitView eventId={eventId} data={data} lifecycle={lifecycle} onChange={load} />}
+    </div>
+  );
+}