resolve issues with new features

frontend/src/components/chat/ChatPanel.tsx

@@ -3,6 +3,7 @@ import Box from '@mui/material/Box';
 import Paper from '@mui/material/Paper';
 import IconButton from '@mui/material/IconButton';
 import ChatIcon from '@mui/icons-material/Chat';
+import OpenInNewIcon from '@mui/icons-material/OpenInNew';
 import Typography from '@mui/material/Typography';
 import Avatar from '@mui/material/Avatar';
 import Badge from '@mui/material/Badge';
@@ -12,6 +13,10 @@ import List from '@mui/material/List';
 import ListItem from '@mui/material/ListItem';
 import { useLayout } from '../../contexts/LayoutContext';
 import { ChatProvider, useChat } from '../../contexts/ChatContext';
+import { Link } from 'react-router-dom';
+import { useQuery } from '@tanstack/react-query';
+import { configApi } from '../../services/config';
+import { safeOpenUrl } from '../../utils/safeOpenUrl';
 import ChatRoomList from './ChatRoomList';
 import ChatMessageView from './ChatMessageView';
 
@@ -22,6 +27,12 @@ const EXPANDED_WIDTH = 360;
 const ChatPanelInner: React.FC = () => {
   const { chatPanelOpen, setChatPanelOpen } = useLayout();
   const { rooms, selectedRoomToken, selectRoom, connected } = useChat();
+  const { data: externalLinks } = useQuery({
+    queryKey: ['external-links'],
+    queryFn: () => configApi.getExternalLinks(),
+    staleTime: 10 * 60 * 1000,
+  });
+  const nextcloudUrl = externalLinks?.nextcloud;
 
   if (!chatPanelOpen) {
     return (
@@ -120,15 +131,24 @@ const ChatPanelInner: React.FC = () => {
         <Typography variant="subtitle1" fontWeight={600}>
           Chat
         </Typography>
-        <IconButton size="small" onClick={() => setChatPanelOpen(false)} aria-label="Chat einklappen">
-          <ChatIcon fontSize="small" />
-        </IconButton>
+        <Box sx={{ display: 'flex', alignItems: 'center', gap: 0.5 }}>
+          {nextcloudUrl && (
+            <Tooltip title="In Nextcloud öffnen" placement="bottom">
+              <IconButton size="small" onClick={() => safeOpenUrl(`${nextcloudUrl}/apps/spreed`)} aria-label="In Nextcloud öffnen">
+                <OpenInNewIcon fontSize="small" />
+              </IconButton>
+            </Tooltip>
+          )}
+          <IconButton size="small" onClick={() => setChatPanelOpen(false)} aria-label="Chat einklappen">
+            <ChatIcon fontSize="small" />
+          </IconButton>
+        </Box>
       </Box>
 
       {!connected ? (
         <Box sx={{ p: 2 }}>
           <Typography variant="body2" color="text.secondary">
-            Nextcloud nicht verbunden. Bitte verbinden Sie sich in den Einstellungen.
+            Nextcloud nicht verbunden. Bitte verbinden Sie sich in den <Link to="/settings" style={{ color: 'inherit' }}>Einstellungen</Link>.
           </Typography>
         </Box>
       ) : selectedRoomToken ? (