admin: fix timestamps, per-day stats, reset, delete drinks/bars

- store created_at as UTC ISO; display/group in Europe/Berlin
- stats grouped by business day (sales night past midnight, 5am cutoff)
- add "Statistik zurücksetzen"
- allow deleting drinks/tresen (refused if referenced by sales)
- CSV exports local wall-clock time

client/src/admin/Admin.tsx

@@ -10,6 +10,7 @@ interface Drink { id: number; name: string; price_cents: number; archived: numbe
 interface BarRow { id: number; name: string; pfand_cents: number; drink_ids: number[] }
 interface Totals { bar_id: number; bar_name: string; tx_count: number; paid_cents: number; crew_count: number; pfand_returns: number }
 interface PerDrink { drink_id: number; drink_name: string; sold_qty: number }
+interface ByDay { day: string; tx_count: number; paid_cents: number; crew_count: number; pfand_returns: number }
 
 export function Admin() {
   const [authed, setAuthed] = useState<boolean | null>(null);
@@ -76,12 +77,44 @@ function Dashboard({ onLogout }: { onLogout: () => void }) {
   );
 }
 
+function fmtDay(day: string): string {
+  const [y, m, d] = day.split('-');
+  return `${d}.${m}.${y}`;
+}
+
 function Stats() {
-  const [data, setData] = useState<{ totals: Totals[]; per_drink: PerDrink[] } | null>(null);
-  useEffect(() => { fetch('/admin/api/stats').then(j).then(setData); }, []);
+  const [data, setData] = useState<{ totals: Totals[]; per_drink: PerDrink[]; by_day: ByDay[] } | null>(null);
+  function reload() { fetch('/admin/api/stats').then(j).then(setData); }
+  useEffect(reload, []);
+
+  async function reset() {
+    if (!confirm('Wirklich die gesamte Statistik (alle Transaktionen) unwiderruflich löschen?')) return;
+    await fetch('/admin/api/stats/reset', { method: 'POST' });
+    reload();
+  }
+
   if (!data) return <p>Lade Statistik…</p>;
   return (
     <>
+      <div class="row" style="justify-content: space-between">
+        <h2 style="margin:0">Umsatz nach Tagen</h2>
+        <button onClick={reset} style="background:#5a2a2a; border-color:#7a3a3a">Statistik zurücksetzen</button>
+      </div>
+      <table>
+        <thead><tr><th>Tag</th><th>Transaktionen</th><th>Bezahlt</th><th>Crew-Transaktionen</th><th>Pfand zurück</th></tr></thead>
+        <tbody>
+          {data.by_day.length === 0 && <tr><td colSpan={5} class="muted">Noch keine Verkäufe</td></tr>}
+          {data.by_day.map(d => (
+            <tr key={d.day}>
+              <td>{fmtDay(d.day)}</td>
+              <td>{d.tx_count}</td>
+              <td>{formatCents(d.paid_cents)}</td>
+              <td>{d.crew_count}</td>
+              <td>{d.pfand_returns}</td>
+            </tr>
+          ))}
+        </tbody>
+      </table>
       <h2>Umsatz pro Bar</h2>
       <table>
         <thead><tr><th>Bar</th><th>Transaktionen</th><th>Bezahlt</th><th>Crew-Transaktionen</th><th>Pfand zurück</th></tr></thead>
@@ -153,6 +186,13 @@ function Drinks() {
     reload();
   }
 
+  async function del(d: Drink) {
+    if (!confirm(`Getränk „${d.name}“ wirklich löschen?`)) return;
+    const res = await fetch(`/admin/api/drinks/${d.id}`, { method: 'DELETE' });
+    if (!res.ok) { alert(`Fehler: ${(await res.json().catch(() => null))?.error ?? await res.text()}`); return; }
+    reload();
+  }
+
   return (
     <>
       <h2>Getränke</h2>
@@ -174,9 +214,12 @@ function Drinks() {
               </td>
               <td class={d.archived ? 'muted' : ''}>{d.archived ? 'archiviert' : 'aktiv'}</td>
               <td>
-                <button onClick={() => patch(d.id, { archived: !d.archived } as any)}>
-                  {d.archived ? 'aktivieren' : 'archivieren'}
-                </button>
+                <div class="row" style="margin:0">
+                  <button onClick={() => patch(d.id, { archived: !d.archived } as any)}>
+                    {d.archived ? 'aktivieren' : 'archivieren'}
+                  </button>
+                  <button onClick={() => del(d)} style="background:#5a2a2a; border-color:#7a3a3a">löschen</button>
+                </div>
               </td>
             </tr>
           ))}
@@ -298,6 +341,13 @@ function Bars() {
     reload();
   }
 
+  async function delBar(b: BarRow) {
+    if (!confirm(`Tresen „${b.name}“ wirklich löschen?`)) return;
+    const res = await fetch(`/admin/api/bars/${b.id}`, { method: 'DELETE' });
+    if (!res.ok) { alert(`Fehler: ${(await res.json().catch(() => null))?.error ?? await res.text()}`); return; }
+    reload();
+  }
+
   async function addBar() {
     const name = newName.trim();
     if (!name) return;
@@ -338,6 +388,7 @@ function Bars() {
                 }
               />
             </label>
+            <button onClick={() => delBar(b)} style="background:#5a2a2a; border-color:#7a3a3a; margin-left:auto">Tresen löschen</button>
           </div>
           <BarDrinkEditor
             bar={b}