Admin: Reiter Matches und Einstellungen, Discord-Embeds, CSTV-Zugang

Der Admin-Bereich bekommt Reiter. Die Discord-Einstellungen liegen
unter „Einstellungen“. Meldungen sind als Embeds formatiert, und die
Match-Startmeldung enthält den CSTV-Zugang (Passwort und Adresse).

client/src/pages/AdminPage.jsx

@@ -29,6 +29,7 @@ export default function AdminPage() {
   const [error, setError] = useState(null);
   const [notice, setNotice] = useState(null);
   const [busy, setBusy] = useState(null);
+  const [tab, setTab] = useState('matches');
 
   const logout = useCallback(() => {
     api('/admin/logout', { method: 'POST', token }).catch(() => {});
@@ -92,17 +93,22 @@ export default function AdminPage() {
         <button className="btn btn-sm" onClick={logout}>Abmelden</button>
       </header>
 
-      {token && <NotificationSettings token={token} setNotice={setNotice} />}
+      <nav className="admin-tabs" aria-label="Admin-Bereiche">
+        <button className={`admin-tab ${tab === 'matches' ? 'is-active' : ''}`} onClick={() => setTab('matches')}>Matches</button>
+        <button className={`admin-tab ${tab === 'settings' ? 'is-active' : ''}`} onClick={() => setTab('settings')}>Einstellungen</button>
+      </nav>
+
+      {tab === 'settings' && token && <NotificationSettings token={token} setNotice={setNotice} />}
       {notice && <div className={`toast toast-${notice.tone}`} role="status">{notice.text}</div>}
       {error && <div className="alert alert-error">{error}</div>}
-      {matches === null && !error && <p className="muted">Lade Matches …</p>}
-      {matches && matches.length === 0 && <p className="muted">Noch keine Matches.</p>}
+      {tab === 'matches' && matches === null && !error && <p className="muted">Lade Matches …</p>}
+      {tab === 'matches' && matches && matches.length === 0 && <p className="muted">Noch keine Matches.</p>}
 
-      <div className="admin-list">
+      {tab === 'matches' && <div className="admin-list">
         {matches?.map((m) => (
           <MatchAdminCard key={m.id} m={m} run={run} busy={busy} token={token} reload={load} setNotice={setNotice} />
         ))}
-      </div>
+      </div>}
     </div>
   );
 }